We all know that we sweat when we are hot, anxious or embarrassed – it’s less well known that sweat actually carries emotional messages
In 1934, a British physician named BA McSwiney stood before his colleagues at the Royal Society of Medicine and lamented that most folks didn’t concern themselves with the chemical composition of human perspiration. Instead, they focused solely on the mechanisms by which the evaporation of sweat from the skin’s surface allowed the body to cool itself.
But McSwiney knew that there was more to sweating than just evaporative cooling. Under certain conditions “the loss of constituents of blood-plasma by continued sweating may be considerable”. In other words, other stuff leaves the body in our sweat. But what kind of stuff, and is its loss a good thing or bad?
Some substances in our sweat we probably wouldn’t want to lose. Take chlorides. These compounds – chlorine atoms, often attached to sodium ones to form salt – are important for maintaining the body’s internal pH balance, regulating the movement of fluids in and out of cells, and transmitting impulses across nerve fibres. It’s normal for some chlorides to leak out of the body as we sweat, but there are some instances in which a person might lose too many. Imagine working for several hours in a hot place, for example. Most of us would know to drink water to stay hydrated. But sweat too much and drink too much and you might start to show symptoms of water poisoning. In those circumstances the body just can’t replace the chloride lost in sweat fast enough.
Also mixed in with sweat is urea, the substance for which urine is also named. By at least one estimate, between 0.24 and 1.12 milligrams of the stuff is dissolved in every cubic centimetre of sweat. That might not sound like much, but given that a person sweats some 600 to 700 cubic centimetres worth of liquid each day, sweat is responsible for up to 7% of someone’s daily elimination of urea. (For comparison, that much sweat would just about fill up a can made for pineapple chunks.)
Then there’s ammonia, proteins, sugars, potassium and bicarbonate. Not to mention trace metals like zinc, copper, iron, nickel, cadmium, lead, and even a tiny bit of manganese. For some of those metals, sweat is an important mechanism for excreting them from inside of the body.
Not all of the things that leak out in our sweat are chemical in nature
Sweat exits the body through one of two types of glands. Apocrine glands are found in the armpits and nostrils and on the nipples, ears and parts of the genitalia. Much more common, however, are eccrine glands, millions of which are distributed over most of the rest of the human body – everywhere except the lips and the genitals. When the body and skin get too warm, thermoreceptors send a message indicating as much to the brain. There, the hypothalamus – a small cluster of cells that controls our hunger, thirst, sleep, and body temperature – sends a message to the apocrine and eccrine glands, which begin pumping out sweat.
There is also a third type of sweat gland, first discovered in 1987. It’s only been found in the same places that apocrine glands show up, but because researchers couldn’t classify them as apocrine or eccrine, they became known as apoeccrine glands. Some think that they are eccrine glands that become somehow modified during puberty.
Tool for communication
Not all of the things that leak out in our sweat are chemical in nature. Everybody has, at some point or other, started to sweat because they ate something spicy, and most people are familiar with emotional sweating due to fear, shame, anxiety, or pain. It’s no wonder that it’s the palms, forehead, and foot soles that are so commonly associated with emotional sweating: eccrine sweat glands there are clustered far more densely, up to 700 per square centimetre, than they are on, say, your back, where there are just 64 per square centimetre.
It turns out that emotion-induced sweating is an important tool for communication. In fact, the scents that we detect in sweat can tell us a lot about how others are feeling.
In one experiment, a quintet of Utrecht University psychologists collected sweat samples from 10 men as they watched videos designed to evoke feelings of fear (excerpts from The Shining) or disgust (excerpts from MTV’s Jackass). In order to avoid odour contamination, the volunteers agreed to forego smelly foods, alcohol, smoking, and “excessive exercise” for two days prior to their sweat donation session.
Then, 36 women were asked to see whether they could detect any emotional cues hidden in the sweat samples. The researchers found that when women were exposed to fear-derived sweat samples, their own facial expressions suggested fear as well. And when they were exposed to disgust-based sweat samples, their faces mirrored that emotion too. (Sweat collection pads that remained unused served as controls; these didn’t cause the participants to show any predictable sort of facial expression.)
People who sniffed the sweat of scared skydivers became aroused in response to angry faces
That suggested to the researchers that sweat appears to be an effective means of transmitting an emotional state from one person to another. Importantly, the facial expressions the women made while sniffing the sweat were completely independent of their subjective perceptions of the odours’ pleasantness or intensity. So they might show a look of disgust even if they reported a particular sweat sample as smelling pleasant.
Similar patterns have also been seen in other experiments. In 2006, Rice University psychologists discovered that women exposed to sweat samples collected from fearful donors (this time the sweat came from both men and women) performed better on a word association task than women exposed to sweat produced by people watching neutral videos, or by sweat pads that contained no sweat at all. The fear-related cues gave them a heightened awareness of their environment.
And in 2012, psychologists and psychiatrists from the State University of New York extracted sweat from the t-shirts of 64 donors. Half of the donors jumped out of an aeroplane for the first time, while the other half exercised really hard. People who sniffed the sweat of scared skydivers became aroused in response to angry faces, but also to neutral and ambiguous ones. Psychologists refer to it as vigilance; the freefall-invoked sweat induced participants to pay attention to whatever possible subtle social cues that they might otherwise have overlooked. Those who sniffed the sweat of exhausted exercisers only became more alert when viewing angry faces, as would be expected under any circumstance.
Yet another experiment conducted by German psychologists and neuroscientists found that sweat from anxious men (who participated in a high ropes course) caused women to make riskier decisions – after spending more time deliberating on their choices – in a computer game designed to assess risk-taking behaviours.
Our ancestors took advantage of the olfactory data constantly flowing into their noses
None of these studies indicate whether people are aware that other people’s sweat has altered their own cognition or behaviour, but they do suggest that sweat might, in some cases at least, communicate important information about our internal mental states. They also suggest that we use the information contained in other people’s sweat to better understand our surroundings.
Perhaps that’s not surprising. Our species may be adapted to verbal and linguistic communication, but language is a fairly new item in our social toolkit. It seems reasonable to imagine that our ancestors took advantage of the olfactory data constantly flowing into their noses – and that they passed the skill down to us.
Indeed, people seem better able to identify emotions in virtual humans on a computer screen when the animated characters visibly perspire. And not only that, but the addition of sweat seems to allow people to perceive the intensity of a displayed emotion. Sweat, in other words, isn’t just a smelly signal, but a visual one too.
Sweat, in the end, is more than just the body’s air conditioning system. It just might be an emotional weather vane as well, a tool used for broadcasting our innermost feelings to our friends and family.
Lachlan Chisholm (Physiotherapist) for Runner’s Tribe and The Source
The Achilles tendon is a very common injury area in running and sport in general. Injury to the Achilles has a multitude of potential causes. The most common site of injury is an Achilles tendinopathy to the mid portion of the tendon, the other common site is the insertion to the heel. There are also other pain causing structures around the Achilles including the retrocalcaneal bursa and subcutaneous calcaneal bursa.
The way we treat tendons has changed over the last few years and will continue to evolve as our understanding of tendon injuries continues to improve. From my experience, each tendon injury responds slightly differently so it is hard to give specifics in this kind of forum. So I will focus mostly on general injury prevention advice and general advice in regards to the current methods of Achilles rehabilitation.
The Achilles connects the calf muscles (gastrocnemius and soleus and plantaris) to the Calcaneus (heel bone) and allows you to plantarflex, or point your foot/ankle. The Achilles is the thickest and strongest tendon in the body, and the tendon can receive a load stress 7.7 times body weight when running, in my case of a 75kg middle distance runner that is up to 577 kg per step! However, if that force is not applied in a longitudinal manner, say a lateral force is applied, it becomes weak and very susceptible to injury. So, as you can imagine the Achilles takes a lot of the load which also makes it susceptible to injury if it is overloaded or loaded in the wrong way.
The best way to treat an Achilles injury is to prevent it in the first place, so my main tips for prevention of Achilles injuries are;
- Adequate strength and flexibility– As a general rule I expect all of my running patients to be able to do 30 (slowly 1sec up 1sec down with good control and alignment) single leg heel raises. I also aim for a minimum of 12cm knee to wall (have your toe 12cm from a wall and keeping your heel on the ground lunge your knee forward to touch the wall).
- No compressive loads– This means you cannot have anything pressing into your Achilles. Sometimes the back of a shoe, for example, can press into your Achilles and this changes the line of force through the Achilles causing an inappropriate load, leading to Achilles tendonitis.
- No sudden changes in load– By this, I mean no rapid increases in training volume, type or surfaces, and type of shoes. When it comes time to move through phases of training this must be done gradually over a period of weeks to allow the body to adapt to the new load whether it be increased volume or increased intensity of training. The same applies for training surfaces and your change from normal training shoes to flats and spikes. (The lower heel in your spikes means your ankle range of motion (ROM) increases when you run which increases the time and ROM your Achilles is under load. This also includes getting adequate rest/recovery between sessions.
- Appropriate footwear- This one can be a tricky subject with the minimalist/maximalist debate. Basically, you need a shoe that fits your foot type and fits comfortably and that is not worn out. I generally find I get between 500-700km out of a pair of shoes before they feel “dead” and are showing significant crush signs on the cushioning.
If you are unlucky enough to develop Achilles pain you really should see a physiotherapist or other appropriate health care professional as soon as you can. But in terms of general advice, this is what I give my patients.
Often the first signs of an Achilles tendinopathy is your first step or two out of bed in the morning, the back of your heel feels stiff and sore but after a few steps/minutes the pain goes away and you think no more of it. This is the best time to get onto it and get proactive about treating it. Basically a bit of ice, gentle stretching, self-massage/foam rolling, and a little bit of relative rest (reduced load). You can also make a start on controlled loading i.e. heel raises/strength.
But once you have passed that point you will notice it when you start to run but again it “warms up” so you continue to train as normal. At this stage, I am not against continuing to train through an Achilles injury as long as it is carefully monitored and managed and is improving with the right treatment and management. However, it tends to improve faster in my experience with modified training or cross training.
You should monitor your morning pain and use this as a guide as to how your Achilles is progressing. Monitor how bad out of 10 the pain is with your first few steps in the morning and how long it takes to go away? If it is getting worse you are doing too much and need to reduce the load.
As above, you want to ice and self-massage and some gentle stretching (if part of your problem is reduced range of motion). Then you need to start loading your tendon in a safe and controlled manner. Tendon healing responds to load, if it is loaded correctly, you can end up with a strong pain-free tendon at the end of your rehabilitation. If not you often end up with a stiff sore tendon and long term problems.
At this point you start out with a period of isometric loading in a neutral ankle position (i.e. not up on your tippy toes and not hanging your heel off a step. Your heel should be held just off the ground or a step – but held at the step height) for 45sec x 3 x 2 daily. Do this on one leg at a time and repeat on the other leg. I use 4/10 as a guide on pain if you are getting over 4/10 pain start by doing both legs at the same time. You will often find that after doing this you have a short pain-free or reduced pain period. It also seems to improve muscle activation. After a week or so you modify this by adding a set of heel raises in between each isometric hold. The number depends on your strength but I often start with 8-10 and progress to 15. As you improve you then reduce the isometric loading to be used as a pain management/ warm up tool and then progressively increase the number of heel raises until reaching 30 single leg heel raises.
You should continue to perform these exercises for up to 12 months once pain-free, as tendon repair and remodelling continue long after your pain has ceased.
About Lachlan Chisholm
Lachlan is a physiotherapist and was one of Australia’s leading 1500m runners for many years. His 1500m PB is 3:37 and he is a two-time Australian 1500m champion.
Exercise scientists have declared that the Tour de France is the hardest endurance event in the world, but what does that actually mean? To help understand, longtime pro-cyclist trainer and researcher Iñigo San Millán, PhD, explains what is going on inside the riders as they make their way across 3,500 km (2,200 mi) over 3 weeks in July.
Stress Hormones Skyrocket
Production of stress hormones like cortisol rises pretty much out of the gate, says longtime pro-cyclist trainer and researcher Iñigo San Millán, PhD, director of the Exercise Physiology and Human Performance Laboratory in Boulder, Colorado.
“The first week is extremely nervous. It’s intense and stressful and riders aren’t sleeping very well,” he says. All of this sends their cortisol levels through the roof. Unless they are able to relax and recover during that first week, the elevated stress hormones will make them prematurely catabolic (i.e., their muscle tissue breaks down), which is bad news because they’ll need every ounce of muscle they have to make it through the Tour de France’s three grueling weeks of riding.
Muscles Break Down
“Though many make it through the first week pretty well if they stay on top of their fueling and recovery, eventually many become catabolic as they head into the mountains,” he says. While in the first week riders may burn just 3 to 5 percent of protein stores (i.e., their muscles) to fuel their efforts, he says, by the final week they’re likely to burn up to 15 to 20 percent as their muscles become increasingly damaged, catabolic, and less able to store and supply glycogen.
Glycogen Storage Capacity Diminishes
About that glycogen: Despite eating diets composed roughly 75- to 80-percent of carbohydrates, San Millán says—with a whopping 25 percent of calories (or 2,000 calories out of the 6,000 to 9,000 they’re eating each day) being simple sugars—Tour riders have a hard time keeping up with their fueling needs by midway through the Tour.
“They’ve sustained so much muscle damage, their muscles no longer have the same capacity to store it,” he says.
Hemoglobin Levels Drop
You rip through 200 billion red blood cells every day when you’re not desperately dangling off the peloton on the 17th hairpin turn up Alpe d’Huez. When you’re not under such duress, you also can create more red blood cells and soldier on.
Not so much during the Tour, when athletes’ blood simply can’t keep up with the mass destruction.
“[Riders’] oxygen-carrying capacity as measured by their hemoglobin concentration decreases from a healthy 15 or 14 grams per deciliter at the start [of the Tour] to 12 to 13 grams per deciliter by the time they cross the finish line in Paris,” says San Millán. Not only does that make them pseudo-anemic, but it also impairs their immune systems, so they’re more vulnerable to getting ill as the Tour wears on.
Free Radicals Increase
Today’s athletes generally aren’t advised to take antioxidant supplements, now that we know popping these pills actually interferes with important training adaptations—like your body’s ability to generate its own natural antioxidants—and can lead to performance detriment rather than enhancement. The Tour is a different beast, however, says San Millán.
“Between the second and third week the body starts losing its ability to produce enough antioxidants to keep up with the daily six-hour free-radical onslaught,” he says, which also impedes immunity. In this case, some antioxidant supplements may be in order.
Heart Rate Declines
During the first week of the Tour, riders can hit their max heart rate no problem. Especially during those first three to five days, they’ll look down and see 190bpm or so and feel stoked.
By the last week, though, they may be excited to see numbers in the 160s to 170s, says San Millán. A lower max heart rate means your heart cannot beat fast enough to keep up with the work you’re doing, and results from being overtrained.
Regardless, the riders will probably be most excited to see the finish line on the Champs-Élysées, so they can finally give their heart and the rest of their tattered bodies a well-earned rest!
Stephen M. Roth, a professor in the department of kinesiology at the University of Maryland, explains
As our bodies perform strenuous exercise, we begin to breathe faster as we attempt to shuttle more oxygen to our working muscles. The body prefers to generate most of its energy using aerobic methods, meaning with oxygen. Some circumstances, however—such as evading the historical saber tooth tiger or lifting heavy weights—require energy production faster than our bodies can adequately deliver oxygen. In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate through a series of steps. When the body has plenty of oxygen, pyruvate is shuttled to an aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown—and thus energy production—to continue. The working muscle cells can continue this type of anaerobic energy production at high rates for one to three minutes, during which time lactate can accumulate to high levels.
A side effect of high lactate levels is an increase in the acidity of the muscle cells, along with disruptions of other metabolites. The same metabolic pathways that permit the breakdown of glucose to energy perform poorly in this acidic environment. On the surface, it seems counterproductive that a working muscle would produce something that would slow its capacity for more work. In reality, this is a natural defense mechanism for the body; it prevents permanent damage during extreme exertion by slowing the key systems needed to maintain muscle contraction. Once the body slows down, oxygen becomes available and lactate reverts back to pyruvate, allowing continued aerobic metabolism and energy for the body’s recovery from the strenuous event.
Contrary to popular opinion, lactate or, as it is often called, lactic acid buildup is not responsible for the muscle soreness felt in the days following strenuous exercise. Rather, the production of lactate and other metabolites during extreme exertion results in the burning sensation often felt in active muscles, though which exact metabolites are involved remains unclear. This often painful sensation also gets us to stop overworking the body, thus forcing a recovery period in which the body clears the lactate and other metabolites.
Researchers who have examined lactate levels right after exercise found little correlation with the level of muscle soreness felt a few days later. This delayed-onset muscle soreness, or DOMS as it is called by exercise physiologists, is characterized by sometimes severe muscle tenderness as well as loss of strength and range of motion, usually reaching a peak 24 to 72 hours after the extreme exercise event.
Though the precise cause of DOMS is still unknown, most research points to actual muscle cell damage and an elevated release of various metabolites into the tissue surrounding the muscle cells. These responses to extreme exercise result in an inflammatory-repair response, leading to swelling and soreness that peaks a day or two after the event and resolves a few days later, depending on the severity of the damage. In fact, the type of muscle contraction appears to be a key factor in the development of DOMS. When a muscle lengthens against a load—imagine your flexed arms attempting to catch a thousand pound weight—the muscle contraction is said to be eccentric. In other words, the muscle is actively contracting, attempting to shorten its length, but it is failing. These eccentric contractions have been shown to result in more muscle cell damage than is seen with typical concentric contractions, in which a muscle successfully shortens during contraction against a load. Thus, exercises that involve many eccentric contractions, such as downhill running, will result in the most severe DOMS, even without any noticeable burning sensations in the muscles during the event.
Given that delayed-onset muscle soreness in response to extreme exercise is so common, exercise physiologists are actively researching the potential role for anti-inflammatory drugs and other supplements in the prevention and treatment of such muscle soreness, but no conclusive recommendations are currently available. Although anti-inflammatory drugs do appear to reduce the muscle soreness—a good thing—they may slow the ability of the muscle to repair the damage, which may have negative consequences for muscle function in the weeks following the strenuous event.
“If you’re not testing, you’re guessing” is a revolving yet relevant saying within the world of sport. This isn’t to say that basing training on feel is over, far from it. Perception and ‘sensory data’ of how your body is responding is the most critical and influential piece of the athletic-puzzle. However, in the midst of heavy training it becomes natural to associate tiredness as the new everyday norm, which often makes it difficult to determine when that thin red line has been crossed… until it’s too late.
For decades physiological testing and monitoring was reserved for the few, given its cost and invasiveness. The bio-tech revolution has changed that, putting physiological tools into our hands in the shape of smart-phones and watches. With a few apps, metrics can now be monitored to allow any level of athlete to get closer than ever before to reaching their potential.
Unfortunately your phone cannot (at least yet) draw and analyse your blood or provide physiological testing, so the lab maintains a pivotal place. Still, in terms of day-to-day monitoring there are several key performance indicators which can be tracked, as explained by Dr. Kevin Sprouse of Podium Sports Medicine, who is also the team physician and Medical Director of the Cannondale-Drapac Pro Cycling Team.
I recommend that you track some metrics every day. For some, this seems onerous. If you are one of those who are not inclined to delve into daily metrics, I’d suggest you start with some very basic ones. Here’s a list that starts with the most basic and moves toward the more involved. Every active person with a goal-driven training plan should be following one or more of these metrics daily! If you use software like Training Peaks, you can even journal your data for the purposes of trending.
Resting Heart Rate – Simply a measure of your heart rate when you first wake up, before leaving bed. Can give you information on your overnight recovery and whether you may need to alter your training plan to avoid illness or injury. You can even get free smartphone apps that will measure your heart rate with the camera! No excuses!
Subjective Evaluation – What does that mean? Basically, it’s listening to your body. Easy, right? Too many of us start the day by looking at our email inbox and text message stream before even getting out of bed! By that time, who knows how you are really feeling!?! Take the first 30 minutes of every day (at a minimum) to ease into the day and get in touch with yourself and your body. (Sounds like crazy hippy talk!) Seriously, sports science research shows that your subjective evaluation is very predictive of your current readiness for training. How did you sleep? Are you sore from yesterday? Starting to feel a little sick? Ready to tackle Mt. Everest? Those feelings are important. Even sophisticated software for gauging recovery (like RestWise) puts significant emphasis on this data. You should too.
Sleep – Many fitness trackers will now also track your sleep patterns, some with much greater accuracy than others. This is a simple metric which can be collected, quite literally, while you sleep!
Heart Rate Variability – Without going into a long explanation, HRV is a measure of the time difference between heart beats. A high level of variability generally indicates a high level of recovery. Measuring HRV is a bit more involved and “scientific” than some athletes care to bother with. But for those who spend the extra 3-5 minutes each morning, this can be something that can truly help to guide training. You can now get smartphone apps that do this in a rather inexpensive but accurate manner. If you are not interested in manually taking the time to collect this data each day, some advanced fitness trackers are now doing this while you sleep. I’ve been using a WHOOP band which measures sleep, HRV, temperature, physiologic strain throughout the day, and more. It’s pricier than a smartphone app, but it does all the work for you. There are other devices that will do this as well (the OURA Ring is one which is less expensive but that I found less reliable when measuring sleep), and many of the more advanced sports watches are starting to implement some of this technology.
Weekly / Monthly Measures
Body Weight – I don’t see much utility in measuring your weight daily, but it can be a useful metric when collected at the same time each week. If your sole goal is weight loss, you may not want to even check it that often. But for those athletes who are following a performance-oriented training plan, you’ll want to see that you are not gaining or losing weight too quickly. Weight gain could indicate water retention and inflammation. Excessive weight loss could be due to inappropriate nutritional fueling. Both are undesirable.
Body Composition – With the advent of technology that makes body composition measurement simple and accurate, many athletes will want to follow this monthly. Most people want to decrease fat mass in increase muscle. Using something like an inexpensive ultrasound measurement of body fat (MuscleSound) can give you regular data to assess whether your training plan is working. If you are loosing weight but much of that is muscle, you are setting yourself up for failure. Take a look to see how you are responding to your training.
Training Load / Training Stress – Most of the metrics I’ve mentioned look at how your body responds to training. In order to know how to modify that training load, you must have some objective measure of it. The most ubiquitous measure is TSS (or “Training Stress Score”). I’d guess that most training software and online training diaries now use this metric, or some variation of it. We won’t delve into its meaning here, but you can read about it on Training Peaks’ website if you are unfamiliar or need a refresher. Whatever you follow, you need to know the intensity and duration of your training. Without these metrics, you’re just making blind adaptations, which probably won’t go well.
Quarterly / Semi-annually
Body Composition – This deserves a place here as well. If you are not tracking this metric every 4-6 weeks, then you’ll definitely want to check it a few times per year!
Blood Tests – After your initial blood work at the beginning of the season, you’ll surely have some things you need to reassess. If your iron levels were low and you’ve been supplementing, you’ll want to recheck that. Likewise, athletes need to ensure that an increased training load has not led to any problems. A quick test every 4-6 months is warranted for any active individual with a goal of health and athletic performance.
Strength and Movement Assessment – You underwent this assessment at the beginning of the year, were prescribed some personalized corrective exercises, and have been diligent in doing them regularly. But increased training load and the rigors of competition (and of life in general) can often lead to changing mechanical stressors. A mid-year checkup is often well worth it!
Physiologic Testing – Your goal is to get fitter. You’ve spent months strictly following a training plan with the aim of increasing your aerobic capacity and the speed at which you can compete. How do you know you’ve been optimally successful? You need to retest! A repeat lactate threshold test, +/- VO2max, at mid-season is crucial to ensuring your training plan is responsive and continues to stress you appropriately.
A very popular belief in sports is that in order to get maximum effect of caffeine in competition you need to withdraw from caffeine in the days or even weeks leading up to it. The theory is quite attractive, because it seems to make sense that some caffeine habituation will take place.
It is believed that non coffee drinkers or those that drink very little coffee will benefit more from caffeine. However, a study in the Journal of Applied Physiology appeared recently that seems to dispel this myth.
The study performed at the University of São Paulo in Brazil used a double-blind, crossover, counterbalanced design. Forty male endurance-trained cyclists were allocated into groups according to their daily caffeine intake:
Low (58 ± 29 mg/d or approximately 1 small cup of coffee), moderate (143 ± 25 mg/d or roughly 2-3 cups of coffee), and high consumers (351 ± 139 mg/d or roughly 5 cups of coffee per day). Participants performed 3 time trials (lasting approximately 30min) each before which they ingested a moderate dose of caffeine (CAF: 6 mg/kg body weight), placebo (PLA), or no supplement (CON). Caffeine and placebo were administered in capsules and ingested 1h before the start of the time trial.
Caffeine supplementation improved exercise performance by 3.3% compared to CON and 2.4% compared to PLA. These data are comparable with other caffeine studies. More importantly, performance benefits with acute caffeine supplementation during a ~30 min cycling time trial were not different between the groups with low, medium or high habitual caffeine intake. In other words: caffeine worked equally for everyone, low users, medium users as well as high users.
It is always important to discuss single studies in the context of the existing evidence, because one study does not necessarily mean that our views should change. Recently there was a well performed study that suggested that 4 weeks of caffeine supplementation diminished performance benefits of acute caffeine supplementation in low habitual caffeine consumers (< 42 75 mg/d). However, giving low habitual users caffeine for 4 weeks, may be quite different from a habitual, high intake. The study can also not exclude the possibility that high habitual users can still benefit from caffeine. Finally, it does also not mean that refraining from caffeine products will increase the effects of caffeine.
Athletes are often encouraged to refrain from caffeinated products for up to 4 days before supplementing with caffeine to enhance the efficacy of acute supplementation. Despite this, a study by Irwin, et al. showed similar improvements in exercise with caffeine in habitual consumers regardless of a 4 day withdrawal period. Another study by Van Soeren, et al. (the first study that directly addressed this question) showed equal exercise improvements with acute caffeine supplementation in habituated consumers after no, 2-days and 4-days of caffeine withdrawal. In a study we performed many years ago, I remember the observation that the largest performance improvements with caffeine were actually observed in the athletes with the higher caffeine intakes. We did not publish those findings because the number of subjects was probably too small to make firm statements, but the observation is interesting nonetheless.
Thus, it is fair to conclude that the balance of evidence suggests that caffeine withdrawal to get a better effect of caffeine is a myth. The recommendation from us is therefore to maintain your normal caffeine consumption during the preparation for your competition. You will still be able to benefit from the effects of caffeine in competition, and you will avoid any possible withdrawal symptoms in the days before.
Whether they like it or not, athletes often find themselves as frequent flyers. Racing overseas can look glamorous, but what people often don’t see on social media is the struggle of being cramped in an economy-class seat for 16 hours.
As one of the worlds top Ironman triathletes, Sarah Piampiano is no stranger to the struggles of long-distance travel and the impact it can have on performance. This is her routine for making the best out of her time 40,000ft in the sky.
Here the 8 things I think about (and in some cases failed on!) on a long journey:
An obvious tip and widely in practice in the world of travelers, but I cannot emphasize enough the importance of comfortable clothing. I typically wear my Saucony compression tights, a soft, loose-fitting t-shirt, and a pair of shoes (like my fav Saucony Jazz’s) that are easy to slip on and off. I also bring a sweatshirt and usually a jacket of some kind – you never know how hot or cold the planes will be, and when worse come to worse, using the clothing as an extra pillow is great!
I also bring a change of clothes in my carry on. After sitting in the same clothes in stale air for 30 hours, it is nice to put on something fresh and clean!
I have ALWAYS brought my own array of snacks with me to either replace or augment the food offered on the plane, but on this trip we brought it to a whole new level. Prior to my departure my nutritionist, Phil Goglia, created a detailed plan as to exactly what I would eat and when during my trip. When I read the plan, it looked like an incredible amount of food and frequent small meals, but he assured me that it would help with the body’s ability to cope with the travel, as well as retain an eating pattering similar to what I do when I am at home.
For my 28 hour journey I pre-packed the following: 7 hard boiled and peeled eggs; 5 “mashes” (1 mash = ¼ cup dry oats, 1 tbsp almond butter, 1 tbsp jam (only sweetened with fruit juice, not sugar), ¼ cup apple sauce all mixed together….sounds gross but is actually delicious!!); 1 lb grilled chicken cut up into slices; 2 cans of tuna mixed with hummus and veggies (modified tuna salad); 1.5 cups cooked rice and 1 medium sweet potato cooked in coconut oil; 1 large bag of carrot and celery sticks; 3 Justin’s single-serve Chocolate Hazelnut packets; 2 pears; 1 Clif Builder Max bar (Cookie Dough); 1 Clif Builder Bar (Cookies & Cream), 1 Clif Bar (Sierra Trail Mix)
When I prepared what I was supposed to eat I never thought I would get through it all. That is a lot of food! But…shockingly, I’ve never been so happy to have each and every meal. I’ve been hungry throughout the journey and rather than eating foods that only hurt my recovery, I’ve kept a plan I feel great about. And there is really nothing worse than being on a long flight and either starving and being cranky, or having access to food that isn’t great for you. Bottom line – on long flights plan ahead and don’t under-estimate how much food you might eat!
A pillar of travel for me and key to alleviating stress on your body. When I am awake, I strive to drink at least 1 water bottle of water with SOS Hydration every 45 minutes to 1 hour, which allows my body to absorb 3x more water than drinking water alone and limits trips to the bathroom.
Compression and recovery
I have a sensitive body and pretty much anything I do makes me swell. I eat too much junk food. I swell. I don’t move enough. I swell. I fly. I swell. I do an Ironman. I swell.
As a result I do whatever I can to help maximize blood flow and minimize the swelling and negative impact on my body. I always wear my Saucony Compression tights when I travel.
On this trip I have done a combination of other recovery and blood-flow-promoting things. First – I used my MarcPro almost continuously throughout the trip. The MarcPro is like electric-stimulation. You attach pads to your body and select the strength and frequency. It causes fast muscle contraction and helps to flush the lymphatic system. Second – I wear my Saucony Compression socks. And third, if I can (not always a possibility) I try to elevate my feet for at least some portion of the trip
Movement is another key one that I use in conjunction with my frequent trips to the bathroom and to bide time during layovers. Keeping the body moving is really important, so on every trip to the toilet, I do calf raises and stretch my quads, abductors and hamstrings. In my seat I have a small stretch band, and loop that around my knees and do some resisted leg movements. I have two lacrosse balls I use to massage my back and hamstrings in my seat. And during layovers I pull out my foam roller and roll like crazy. I also do my rehab exercises and glute, core and hamstring activation exercises. Don’t worry about the funny looks! Your body will thank you for it later!
When you fly, the best thing you can do is let yourself relax. I was laughing to myself earlier because I felt like a newborn baby on this trip. Pretty much my schedule has been, sleep, eat, toilet, sleep, eat, toilet, etc etc etc…flying is a perfect opportunity to try to get some extra rest and truly let your mind and body detach from the stresses of daily life.
Minimizing the white noise
You may not realize it or think about it, but that white noise you hear the entire plane flight is really hard on your body! It is a constant stimulant and doesn’t fully let your body relax. The best way to shut that out is through using noise-cancelling headphones or ear plugs.
Access to the bathroom
Until I became a triathlete, I loved the window seat. I liked to be able to look out over where we were flying and liked being able to use the plane wall to rest my head. Nowadays, the aisle is the way to go! I have to get up so frequently to move my legs and use the toilet and refill my water bottle, the aisle is the best way to have easy access and avoid ticking off your seat mates.
WHY AM I SO HUNGRY?
It would seem logical that exercise is associated with increased energy expenditure and therefore increased hunger and drive to eat, so why is it that we often feel extra hungry on days off training?
Firstly, let’s revisit some basics of metabolic physiology. Several factors contribute to your hunger levels, not just the amount of activity that you do. There are a number of major players in appetite regulation including:
- Your body composition (especially muscle mass)
- Resting metabolic rate
- Gastric response to ingested food
- Changes in appetite hormones (e.g. insulin, ghrelin, cholecystokinin, glucagon-like peptide-1 and Peptide YY, leptin)
Here are some possible explanations to consider why we feel hungrier on rest days.
HUNGER HORMONES AND EXERCISE
There is evidence that exercise influences all of these components. For example, during times of energy deficit (e.g. the day after a big training day), our appetite hormones are signalling for us to eat more, and this may contribute to increased hunger levels.
On days of high training load/volume, hunger is often suppressed after exercise (especially after vigorous exercise), most likely due to redistribution of blood flow to the extremities, away from the gastrointestinal tract.
There appears to be a delayed compensatory response, whereby a lag of 1-2 days, or longer, seems apparent in order to ‘even out’ days of high(er) energy expenditure. Interestingly, some people are compensators and others not. That is, some eat habitually (the same thing which doesn’t change from day to day) while others eat according to hunger and/or based on the activity completed (or not).
EXERCISE MAY IMPROVE THE SENSITIVITY OF SIGNALLING SYSTEMS TO EAT
The theory (called the ‘glycogenostatis theory’) suggests that glycogen availability has a central role in feedback signals to the body to restore energy balance. After glycogen depletion (which occurs during exercise), one of the body’s priorities is to restore carbohydrate levels in the body. This theory suggests that after exercise the glycogen depletion of the muscles exerts a signal to the body to trigger compensatory eating, which in turn, restocks carbohydrate in the body. The specifics of this signalling pathway are currently relatively unknown and further research is required to fully understand the mechanisms involved.
EXERCISE COULD ALTER MACRONUTRIENT PREFERENCES AND FOOD CHOICES
Another prominent theory suggests that there is a biological drive to seek particular foods to replenish blood sugars or glycogen. This effect could also relate to preferences for particular tastes associated with certain nutrients (e.g. sweetness which is often associated with carbohydrate rich foods).
CATCHING UP FOR MISSED TIME
Some research says that often people don’t always feel hungrier in the couple of days following a bout of exercise, but do feel hungry if they have missed a meal. Translate this to real life and we have the scenario where training may replace time spent eating food, which then leads to an increase in appetite and drive to eat in the days afterwards.
So the good news is that fluctuations in appetite are completely normal. For best health and wellness, it’s a good idea to tune in to your hunger levels and then adjust your eating accordingly.
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