Category Archives: Athletic Performance

Maximize Sleep To Improve Athletic Performance

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail
rss

 

This is part 4 of a series about the importance of sleep to athletes.  Part 1 was “Improve Athletic Performance By Taking A Nap.”  Part 2 was “Reduced Quality Of Sleep In Athletes.” Part 3 was “The Effect Of Sleep Deprivation On Athletic Performance.” Please subscribe to this blog for future installments and other interesting content.

My wife, Jessica, is an Ultramarathoner (you run an ultra, you get a capital “U”).  I have always been amazed at her powers of recovery. She ran a couple marathons last year as training exercises for a 50 mile race. She can run for hours on one day, then wake up the next day and do it again.  What is her secret?  Aside from being naturally gifted and very determined, she gets a lot of sleep; much more than me.  Is she on to something?  There is some research, in fact, that does demonstrate that extended sleep enhances athletic performance.

All of the most current research on this subject is from one institution, Stanford.  There are some limitations to the study designs and to the accessibility of the data, which will be discussed later.  One study has been published as a full peer-reviewed manuscript and will be the focus of most of this article.  In this study, 11 members of Stanford’s varsity men’s basketball team maintained their usual sleep-wake schedules for 2-4 weeks, then extended their sleep for 5-7 weeks.  During the period of sleep extension, the participants were to obtain as much nocturnal sleep as possible with a minimum goal of 10 hours in bed each night.  Per journal entries, the participants’ sleep increased from a baseline average of 470.0 minutes per night to 624.2 minutes per night during the study period.  Per actigraphy measures, baseline and study measures were 400.7 minutes and 507.6 minutes, respectively.  To translate this information into hours, during the study period the participants were in bed for 10.4 hours and actually slept 8.46 hours. Incidentally, at baseline the participants were sleeping less than 7 hours a night, which is not atypical, but less than national recommendations for sleep (7-9 hours per night). Variables measured included timed sprints (the participants ran a back-and-forth shuttle across the basketball court), shooting accuracy, reaction time, levels of daytime sleepiness, and mood.  At the end of the period of sleep extension, compared with baseline, participants demonstrated a faster sprint time (15.5 seconds vs 16.2 seconds), an increase in free throw shooting accuracy of 9%, an increase in 3-point field goal shooting accuracy by 9.2%, faster reaction time, decreased sleepiness sales, and improved mood, including, during practices and games, improved overall ratings of physical and mental well-being. Incidentally, this improved speed, shooting, and mood did not lead to a better record for the men’s basketball team.  Their record in the 2005-2006 season was 16-14, while it was 18-13 in the previous and subsequent seasons.  There are hundreds of variables that go into the performance of a basketball team over a season, so these results are merely interesting, not instructive.

These Stanford researchers also did very similar studies in varsity swimmers, football players, and tennis players.  The results have only been reported so far in abstract form, and, so, are not available for a great deal of scrutiny.  These studies appeared to show similar results to the basketball players.  For example, swimmers decreased their 15 meter sprint swim times from 6.98 to 6.47 seconds, decreased their reaction times from 0.88 to 0.73 seconds, decreased their turn times from 1.10 seconds to 1.00 seconds, and increased their kick strokes from 26.2  to 31.2, after the period of sleep extension.   The football players decreased their 40 yard dash times from 4.71 seconds to 4.61 seconds, after the period of sleep extension.

There are important limitations to these research findings, however.  The most obvious limitation is the lack of a control group in these studies. It is reasonable to expect that well-coached collegiate athletes will improve their performances over 5-7 weeks and it is unknown if these athletes would have improved, to some degree, regardless of their sleep schedules. My impression, however, is that shooting accuracy and reaction times are unlikely to change so significantly just from coaching and training over 5-7 weeks.  Indeed, the concern for many athletes is fatigue over the course of an athletic season.  These athletes did not appear to experience this fatigue.  Another limitation is the fact that the researchers have not published three of their abstracts, dated 2008, 2009, and 2010, as full manuscripts.  This suggests that their data may have other weaknesses that have led to rejections by medical journals over the past seven years. For busy athletes, however, the most important weakness is the difficulty of applying these results to real life.  Not many people have the flexibility and freedom to be in bed for 10.4 hours every night for an athletic season.

In spite of the limitations of the research presented, it does appear that extended periods of increased sleep do lead to important enhancements in athletic performance.  This effect appears to be applicable to both skills and endurance and to both team and individual sports.

Just like eating right, practicing skills, and training endurance, maximizing sleep can let an athlete reach his or her full potential.

Published March 24, 2015

References:

Mah CD, Mah KE, Dement WC. Extended sleep and the effects on mood and athletic performance in collegiate swimmers. Journal of Sleep and Sleep Disorders Research. 2008;31(Suppl.):0384.

Mah CD, Mah KE, Dement WC. Athletic performance improvements and sleep extension in collegiate tennis players. Journal of Sleep and Sleep Disorders Research. 2009;32(Suppl.):0469.

Oh no...This form doesn't exist. Head back to the manage forms page and select a different form.

Mah CD, Mah KE, Dement WC. Sleep extension and athletic performance in collegiate football.  Journal of Sleep and Sleep Disorders Research. 2010;33(Suppl.):0304.

Mah CD, Mah KE, Kezirian EJ, et al. The effects of sleep extension on the athletic performance of collegiate basketball players.  Sleep. 2011;34:943-950.

 

 

The Effect Of Sleep Deprivation On Athletic Performance

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail
rss

 

This is part 3 of a series about the importance of sleep to athletes.  Part 1 was “Improve Athletic Performance By Taking A Nap.”  Part 2 was “Reduced Quality Of Sleep In Athletes.” Please subscribe to this blog for future installments and other interesting content.

We all miss sleep before important athletic events.  There has been research on the effect of partial and total sleep deprivation on aerobic and anaerobic exercise performance.  This information is important to all athletes, but especially to ultra-endurance athletes who, as a part of competitions become sleep deprived.

While it would be very unusual to not sleep at all before important competitions, it is commonplace to have reduced or disrupted sleep.  The studies that have investigated the effects of such reduced sleep on performance have, surprisingly, not demonstrated a large decrement.  For example, one study described the effects of one night of restricted sleep on athletes and found no change in gross motor function such as muscle strength and endurance running.  Another similar study in females showed similar results with less of an effect upon gross motor functions than tasks that required rapid reaction times.  In a study of eight swimmers, the effect of 2.5 hours of sleep for four consecutive nights was studied and no effect was observed in back and grip strength lung function, or swimming performance.  However, mood state was altered with increases in measures of depression, tension, confusion, fatigue, and anger.  With regard to anaerobic performance, a study examined the effects of a single night of 2.5 hours of sleep in a group of sedentary women and found no change in muscle strength.  However, an effect on anaerobic performance appears to become more apparent after several nights of restricted sleep.  This was demonstrated in a study of the effect of partial sleep loss (3 hours of sleep per night for 3 consecutive nights) on muscle strength. In this study, there was a decrease in maximal bench press, leg press, and deadlift, but not maximal bicep curl.  Interestingly, however, sub-maximal efforts were significantly negatively affected for all four tasks to a greater degree than the maximal efforts. Furthermore, the largest impairments were found later in the protocol, which suggests that there is an accumulative effect of muscle fatigue from sleep loss.  This last study may be of particular interest to long-course triathletes, who rely on muscular endurance, particularly in the cycling leg of races.

In the case of prolonged periods of no sleep, there are some interesting studies that have shown a large effect on performance.  For example, 30 hours without sleep has been demonstrated to lead to decreased running performance  This was shown in a trial in which participants ran, self-paced, on a treadmill for 30 minutes either after normal sleep or after 30 hours without sleep.  The sleep-deprived performances were clearly inferior, with the participants covering an average of 6224 meters after normal sleep and 6037 meters after no sleep.  Interestingly, the sleep-deprived participants had a similar perception of their effort in both performances.  This suggests that sleep deprivation may lead to decreased running performances because of impaired perception of effort.  In another study with similar results, there were significant decreases in average and total sprint time after 30 hours without sleep.  In terms of anaerobic performance, a study of 24 hours of sleep deprivation in weightlifters showed no differences in the tasks measured, including snatch, clean and jerk, front squat, total volume load, and training intensity.  However, the mood state of sleep-deprived participants was significantly negatively affected, including increased confusion.  At 30 hours of sleep deprivation, however there does appear to be an effect on muscle strength.  This was demonstrated in a study that showed decreased knee extension and flexion peak torque after no sleep for 30 hours, as compared to after normal sleep.  The importance of the difference between 24 hours without sleep and longer durations of time without sleep was demonstrated, again, in another study that showed that anaerobic performances were unaffected after 24 hours of wakefulness but were impaired after 36 hours of wakefulness.

So, don’t worry about a single night of reduced sleep before a race.  It does not appear to have a meaningful effect upon athletic performance.  In contrast, a number of consecutive nights of reduced sleep does appear to affect muscle strength, especially sub-maximal strength, but does not appear to affect swimming performance.  With regard to no sleep at all before exercise, 24 hours without sleep has not been shown to affect performance, but 30 hours or more without sleep has been shown to affect both aerobic and anaerobic performance.  For those people who participate in overnight endurance races, either as a solo athlete or as part of a relay team, this information may be particularly important.  Performance in such as situation is impaired and, as described above, an athlete may be unable to perceive this impairment aside from feeling grouchy.

Oh no...This form doesn't exist. Head back to the manage forms page and select a different form.

Published March 22, 2015.

References:

Bambaeichi E, Reilly T, Cable NT, et al. Influence of time of day and partial sleep loss on muscle strength in eumenorrheic females.  Ergonomics. 2005 Sep 15-Nov 15;48(11-14):1499-1511.

Blumert P, Crum AJ, Ernsting M, et al. The acute effects of twenty-four hours of sleep loss on the performance of national-caliber male collegiate weightlifters. J Strength Cond Res. 2007;21:1146-1154.

Bulbulian R, Heaney JH, Leake CN, et al. The effect of sleep deprivation and exercise load on isokinetic leg strength and endurance. Eur J Appl Physiol Occup Physiol. 1996;73:273-277.

Oliver SJ, Costa RJ, Laing SJ, et al. One night of sleep deprivation decreases treadmill endurance performance.  Eur J Appl Physiol. 2009 Sep;107(2):155-161.

Reilly T and Deykin T., Effects of partial sleep loss on subjective states, psychomotor and physical performance tests.  J Human Mov Stud. 1983;9:157-170.

Reilly T and Hales A., Effects of partial sleep deprivation on performance measures in females. Contemporary Ergonomics. Taylor and Francis. ED McGraw (London) 1988:509-513.

Reilly T and Piercy M. The effect of partial sleep deprivation on weight-lifting performance. Ergonomics. 1994;37:107-115.

Sinnerton S, and Reilly T. Effects of sleep loss and time of day in swimmers.  Biomechanics and Medicine in Swimming: Swimming Science IV. Maclaren D, Reilly T, and Lees A. Spon Press (London) 1992:399-405.

Skein M, Duffield R, Edge J, et al. Intermittent-spring performance and muscle glycogen after 30 h of sleep deprivation. Med Sci Sports Exerc. 2011;43:1301-1311.

Soussi N, Sesboue B, Gauthier A, et al. Effects of one night’s sleep deprivation on anaerobic performance the following day. Eur J  Appl Physiol. 2003;89:359-366.

Improve Athletic Performance By Taking A Nap

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail
rss

 

The National Sleep Foundation recommends 7-9 hours of sleep per night for adults age 18-64. Unfortunately, most of us don’t get this much sleep.  This is also true for athletes.  For example, elite athletes in a recent study only obtained an average of 6.8 hours of sleep per night.  In another study of elite athletes, their total time in bed was 8.6 hours, but their sleep quality was poor with a total time asleep of only 6.9 hours.   With travel to events or, simply, pre-race jitters, many athletes experience serious disruptions to their already-inadequate sleep schedules.  These disruptions can affect athletic performance.  The good news, however, is that there is a small study which has shown that sleep-deprived athletes perform better after short naps.

Oh no...This form doesn't exist. Head back to the manage forms page and select a different form.

This study involved 10 healthy males with mean age 23.3 years who either napped or sat quietly from 1 PM to 1:30 PM after a night of shortened sleep (they slept from 11 PM to 3 AM).  Thirty minutes after the nap or quiet sitting, a number of parameters were measured, including alertness, short-term memory, intra-aural temperature, heart rate, choice reaction time, grip strength, and times for 2 meter and 20 meter sprints. The participants who took afternoon naps had lowered heart rate, lowered intra-aural temperature, and improvements in alertness, sleepiness, short-term memory, and accuracy at the choice reaction time test.  Mean reaction times and grip strength were unaffected.  Interestingly, sprint times were also significantly improved, with mean time for 2 meter sprints falling from 1.060 seconds to 1.019 seconds and mean time for 20 meter sprints falling from 3.971 seconds to 3.878 seconds. Please note, again, that these numerous improvements were after only a 30 minute nap.

The practical implications of these findings vary with an athlete’s individual situation.  For example, a triathlete with a 7 AM race-start is hardly going to have an opportunity for a nap. However, a triathlete in a large multi-wave event (like the Transamerica Chicago Triathlon or USAT Nationals) can go back to his or her hotel room after setting up transition and take a short nap.  Athletes in events played later in the day, which includes most professional team sports, can also practically include naps in their schedules.  These scheduled naps can be relatively brief, since this study demonstrated that naps of only 30 minutes can lead to enhancements in performance.

So, have a nice nap and come back and race or train better!

Published March 15, 2015

References:

Lastella M, Roach GD, Halson SL, et al. Sleep/wake behaviours of elite athletes from individual and team sports.  Eur J Sport Sci. 2015 Mar;15(2):94-100

Leeder J, Glaister M, Pizzoferro K, et al. Sleep duration and quality in elite athletes measures using wristwatch actigraphy. J Sports Sci. 2012;30(6):541-545.

Waterhouse J, Atkinson G, Edwards B, et al. The role of a short post-lunch nap in improving cognitive, motor, and sprint performance in participants with partial sleep deprivation. J Sports Sci. 2007 Dec;25(14):1557-1566.

 

 

Athletic Performance Boosted By Bright Light

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail
rss

 

It is possible to boost performance in competitions with a simple intervention: bright light.

In a paper published in 2012, researchers studied 43 male athletes with an average age of 24.5 years.  This was a randomized crossover study, which is a superior study design.  The participants were assessed for chronotype, which is a measurement of an individual’s internal time clock, and testing was performed either an average of 11.78 hours after estimated mid-sleep time for one group (this was the group who went to bed later and awoke later) or an average of 14.79 hours after estimated mid-sleep time for the other group (who went to bed earlier and awoke earlier).  The average actual real-time of the testing was about 5:30 PM.  The researchers chose this later time of day because previous studies have shown that optimal athletic performance is in the later afternoon/early evening. The study protocol involved being exposed to either bright light (approximately 4,420 lx) or dim light (approximately 230 lx) for 160 minutes.  During the final 40 minutes of the ongoing exposure to different levels of light, the participants performed testing on bicycle ergometers.  The finding were remarkable.

Bright Light Dim Light
Total Work 548.4 kJ 521.5 kJ

The participants, when exposed to bright light, also had 12.7% higher levels of blood lactate at exhaustion, 1.8% higher heart rate, and 2.6% higher Borg scale ratings.  Furthermore, the group that was tested three hours later with regard to mid-sleep time produced more work that the group with less time since mid-sleep.  All of these differences were statistically significant.

Therefore, these researchers showed that bright light before and during endurance exercise led to enhanced performance and that exercising an average of 14.79 hours after the time of mid-sleep was superior to exercising three hours earlier.

How does this apply to amateur and professional endurance athletes? We certainly cannot pre-select our start times and almost all competitions start early in the morning.  This is further complicated by the fact that most of us awaken several hours before race time and many of us creep around in the dark to avoid disturbing people around us.  Furthermore, this is a single study performed under very controlled conditions.  It is hard to generalize these findings to real life.

These findings, however, are compelling.  My suggestion is to understand the limitations described, above, but try to apply a few of the concepts.  For example, before a competition, try to be in brightly lit areas for the greatest duration possible.  Many competitions start in the semi-darkness of early dawn, but getting a boost of light before lining up to race, just like eating the right pre-race meal, may enhance performance.

Published March 9, 2015

Reference:

Kantermann T, Forstner S, Halle M, et al. The Stimulating Effect of Bright Light on Physical Performance Depends on Internal Time. PLoS ONE. 2012 7(7):e40655.

 

Oh no...This form doesn't exist. Head back to the manage forms page and select a different form.

 

Athletes: Is Caffeine Cheating?

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail
rss

 

Is your cup of coffee giving you an unfair edge?

The effects of caffeine on the performance of athletes have been studied and described for years.  A number of hypotheses have been suggested to explain these effects within a range of sports.  But is caffeine just a legal, and socially acceptable, form of doping?  Should certain groups: elites, amateurs, or adolescents, be banned or discouraged from using caffeine?

The strongest evidence for the enhancing effects of caffeine on exercise is in endurance sports (hence, the personal interest I have in this topic).  Studies have reported that 3-9 mg of caffeine per kilogram of body weight, consumed one hour prior to exercise, by highly trained runners and cyclists, enhanced their laboratory-measured endurance performances. Therefore, a 160 pound (72.6 kg) person would consume 218-653 mg of caffeine to get 3-9 mg of caffeine per kg of body weight. To put this in familiar terms, a 12 ounce (“tall”) Starbucks brewed coffee contains 260 mg caffeine and the same-sized Starbucks latte contains 75 mg. In contrast, a 12 ounce (“small”) McDonald’s coffee contains 109 mg of caffeine.  One 12 ounce Starbucks brewed coffee or two 12 ounce McDonald’s brewed coffees would provide enough caffeine to be in the dosage range of 3-9 mg/kg for a 160 pound person.

The mechanism to explain these improvements in endurance is unclear.  It has been demonstrated that muscle glycogen (an energy source) is spared early during submaximal exercise after caffeine doses at a range of 5-9 mg/kg.  However, at the lower end of the range of caffeine doses described above (3 mg/kg), there is no evidence that muscle glycogen is spared. Therefore, glycogen sparing is not a complete explanation for the ergogenic effects of caffeine on endurance exercise.

In addition to effects on endurance exercise, caffeine has been shown to improve performance during short-term exercise, lasting approximately 5 minutes, at 90-100% maximal oxygen uptake, in laboratory tests.  Hypotheses about the mechanisms underlying this improvement include enhancement in contraction of muscles, provision of anaerobic energy to muscles, or an effect upon the central nervous system related to sensation of effort.  Sprint performances of up to 90 seconds of intense exercise do not appear to be affected by caffeine.

Oh no...This form doesn't exist. Head back to the manage forms page and select a different form.

Caffeine is defined as a “controlled or restricted substance” by the International Olympic Committee, which limits the amount of caffeine in urine to 12 micrograms per milliliter of urine. It is also restricted by the US National Collegiate Athletic Association, which uses 15 micrograms per milliliter of urine as its limit.  But these limits actually allow for the consumption of a great deal of caffeine.  For example, if an athlete were to consume 9 mg of caffeine per kg of body weight one hour before exercise, then exercise for 60-90 minutes, and then submit a urine sample, this sample would only approach the limit of 12 micrograms per milliliter of urine.  This is about 29 ounces of Starbucks brewed coffee or about 69 ounces of McDonald’s brewed coffee!  On the other hand, doses of caffeine of greater than 6 mg/kg of body weight can lead to a higher chance of side effects such as anxiety, jitters, inability to focus, gastrointestinal upset, insomnia, irritability, and, at higher doses, hallucinations and heart arrhythmias.  Therefore, the optimal dose to enhance performance and minimize side effects appears to be 3-6 mg of caffeine per kg of body weight.

With some basic information about dosing, it is easy for endurance athletes to use caffeine to enhance their performances “within the rules.”  However, is this fair?  What if athletes are at an unfair disadvantage because of religious beliefs, unusual sensitivity to caffeine (susceptibility to migraines, for instance), or, simply, not enjoying caffeinated products?  Another concern is young endurance athletes. A Canadian survey of young (11-18 years old) athletes found that 27% consumed caffeine over the previous year for the specific purpose of enhancing athletic performance.  Is this an indication that caffeine is a “gateway” drug to other, much more dangerous, performance-enhancing drugs?

 Posted March 4, 2015.

 Reference:

 http://www.acsm.org/docs/current-comments/caffeineandexercise.pdf