As coaches, we have the responsibility of providing our athletes with the best opportunity to be successful on the field. We strive to optimize performance through training and nutritional interventions. In an athletes’ pursuit to constantly up their game, they will eventually be confronted with the option of using sport nutrition supplements. In this situation, the coach must consider (at least) 3 important questions concerning a given sport supplement product:
- Is it legal?
- Is it safe?
- Is it effective?
Being able to answer these questions should help the coach guide the athlete to making the most informed decision possible. A review of the available research will ultimately show that very few sport nutrition supplements can substantially improve performance. However, caffeine is one of the supplements that tends have a decent track record of success and its supplementation may be worth exploring.
In a new study published ahead of print in the International Journal of Sports Physiology and Performance, the effects of moderate doses of caffeine ingestion on countermovement jump performance was investigated. A group of 10 elite male volleyball players volunteered for this study. In a randomized, cross-over design, the athletes performed two trials of countermovement jumps on a force plate separated by one week, with or without caffeine. This was a double-blind study, meaning that neither the researchers nor the athletes knew at which trial they were given caffeine in an effort control for bias and placebo effects. Three countermovement jumps were performed following 60-min of placebo or caffeine (5 mg/kg) ingestion. At 24 hours post-trial, all subjects completed questionnaires regarding any potential side effects that may have encountered from the caffeine.
The results showed that caffeine ingestion resulted in significant increases in numerous markers of performance during the countermovement jump including peak concentric force output (6.4%), peak power (16.2%) flight time (5.3%), peak velocity (12.6%) and peak acceleration (13.5%). In addition, caffeine ingestion reduced the time between peak power and peak force (16.7%). Diastolic blood pressure increased by an average of 13% from caffeine ingestion and no adverse side effects were noted from the questionnaires. This study adds to the growing body of evidence demonstrating that caffeine intake may enhance neuromuscular performance in athletes.
Reference: Zbinden-Foncea, H. et al. Effects of Caffeine on Countermovement Jump Performance Variables in Elite Male Volleyball Players. International Journal of Sports Physiology and Performance. In press.
Linear sprinting speed is a highly coveted physical quality by team-sport coaches. Clocking a fast 40 yard dash at the combine can move up an athletes draft status and earn them higher salaries. Therefore, training to improve linear speed is a high priority for many teams. A common way to train for sprinting speed is by having athletes perform assisted and resisted sprinting. Assisted sprint training is intended to have the athlete run slightly faster than they’re capabilities by having them pulled via harness during repetitions or by sprinting on a slight decline (downhill). This is thought to improve stride frequency and train the nervous system to move faster. Sprint resisted training is intended to develop acceleration speed by improving force production. This is accomplished by having athletes tow a weighted sled during repetitions or simply sprint on a slight incline. This method is thought to improve stride length.
A new study published ahead of print in the Journal of Strength and Conditioning Research sought to determine if combined uphill and downhill sprint training was superior to traditional sprint training on a level surface for improving performance markers. A sample of 20 college-aged males with an athletic background were divided into a combined training group (uphill and downhill sprinting on a 4 degree incline/decline) a traditional training group (level surface sprinting only) and a control group (no training). The training sessions were held 3 days’s per week on non-consecutive days over an 8-week period. Overall training volume was similar between groups. Before and after the training period, 100 m sprint time, running velocity, stride frequency, and stride length were tested among all participants.
The results showed that overall 100 m sprint time was improved by an average of ~4% for the combined group and ~2.4% for the traditional group. Running velocity showed similar improvements for both groups (~4.1% for combined and 2.4% for traditional). Stride length and stride frequency improved in both training groups in the 60-90 m phase with improvements being slightly greater for the combined group. These results suggest that both traditional sprint training on level surfaces and uphill and downhill sprint training can lead to improvements in linear sprinting speed, but that combined training may be slightly superior. Therefore, coaches should consider incorporating combined sprint training with their athletes.
Cetin, E., Hindistan, I. E., & Ozkaya, Y. G. (2017). Effect of Different Training Methods on Stride Parameters in Speed Maintenance Phase of 100m Sprint Runningmel. The Journal of Strength & Conditioning Research. In press.
The pre-competition warm-up serves a number of important functions. Some of these include increases in body temperature, heart rate and oxygen consumption, increased muscle contraction speed, increased synovial fluid and joint mobility. These physiological responses can help increase performance and potentially reduce injury risk. The timing of the warm-up before a match can therefore play an important role in team performance early on. Warming up too early with excess wait time before game time may result in a reversal in warm-up effects. While most coaches are aware of this and plan accordingly, the pre-game period is not the only time players should be warming up. For example, post-halftime and before substituting for cold players are both important times where players would benefit from warming up.
A new case study published in the journal “Sports” investigated the physiological responses to warming up and subsequent reversal of these responses from being sidelined. Two high level adult male basketball players volunteer for the study. Before and after a 20 minute warm up and again throughout the first half of a competitive basketball match, performance measures (countermovement jump) and physiological measures (heart rate, core temperature and skin temperature) were obtained. The warm-up was comprised of jogging, dynamic stretches and basketball-specific drills. The researchers wanted to determine if substitute players were physiologically ready to perform after being sidelined for about one half of play.
The results showed that compared to pre-warm-up, post-warm-up countermovement jump height improved by about 7%. After being sidelined for the half, countermovement jump heights dropped between 12 and 15%, nearly 7% below baseline values. Core temperature increased by roughly 1 degree following the warm-up, then progressively reduced (~0.5 degree) throughout the half, though remained above baseline. Skin temperatures peaked during the warm-up and progressively reduced towards baseline from passive rest during the half. Heart rate peaked at 170 – 180 beats per minute during the first 10-12 minutes of warming up. Within 6 minutes of the half, heart rate dropped to <100 beats per minute and continued to progressively decrease towards baseline thereafter. The authors conclude that key performance indicators are reduced and physiological responses to warming up are reversed in substitute players who passively wait on the sidelines to be called in. Thus, having players warm up on the sideline before being sent in may improve performance.
Crowther, R.G., et al. Influence of Rest on Players’ Performance and Physiological Responses during Basketball Play. Sports 2017, 5(2), 27.
Traditionally, sport participation revolved around the academic year where student-athletes could play a seasonal sport. For example, football would be played in the fall, basketball in the winter and baseball or track and field in the spring. This format exposed youth athletes to a variety of movement demands and skill acquisition. In more recent times, young athletes have been given the option of playing a select sport year-round. Club teams, summer teams, tournaments and clinics provide individuals with the opportunity to play and compete in their sport, regardless of season. This has lead to the concept of early specialization where young athletes elect not to participate in other sports in favor of their chosen sport. While it may seem that focusing on one sport may be optimal for performance development, there is a growing body of evidence that suggests that early specialization can be harmful rather than helpful to athletic development.
A new study published ahead of print in the American Journal of Sports Medicine sought to determine if high levels of sport specialization were associated with history of injuries in young athletes. A sample of 2011 youth athletes between the ages of 12-18 years (989 female, 1022 male) completed a survey regarding their level of sport specialization, weekly and yearly sport training volume and their injury history. The athletes were subsequently categorized according to specialization status as low, moderate or high as well as if they were meeting or exceeding the recommended training volume recommendations. Associations between specialization status, training volume and injury occurrence from the preceding year were assessed.
The results showed that athletes categorized as highly specialized had a greater odds of reporting a previous injury of any kind as well as an overuse injury in the previous year compared to athletes with low specialization status (p <0.05). In addition, athletes that participated in a specific sport for more than 8 months of the year had a greater odds of reporting both upper and lower body overuse injuries in the previous year (p <0.05). Finally, athletes participating in more hours of training per week than their age were more likely to have experienced an injury in the previous year (p <0.05). Thus, both high specialization status and exceeding training volume guidelines are associated with greater injuries among youth athletes. As such, parents should limit their children’s sport participation to within the recommended levels as well as encourage participation in a variety of sports.
Post, E. G., Trigsted, S. M., Riekena, J. W., Hetzel, S., McGuine, T. A., Brooks, M. A., & Bell, D. R. (2017). The association of sport specialization and training volume with injury history in youth athletes. The American Journal of Sports Medicine, In Press.
The age old question of “how are you feeling?” is a highly underrated monitoring tool that tends to get overlooked in the current era of advanced sports science technology. Factors such as mood and sleep quality tend to deteriorate when fatigue accumulates and performance starts to suffer. Therefore, tracking this information can be a useful way of keeping tabs on an athletes’ training status. While daily conversations can take place with individual athletes of small teams, asking a large team of athletes “How are you feeling?” can be difficult on a daily basis. Thus, the wellness questionnaire was developed to systematically evaluate perceived well-being in athletes. This information can be collected conveniently and affordably in the field with smartphone applications and analyzed in Excel. Until recently, it’s been difficult to measure the impact of how perceptions of well-being impact performance.
A new study published ahead of print in the Journal of Science and Medicine in Sport evaluated the impact of perceived well-being ratings on training output in elite male soccer players. A total of 48 players from two professional soccer teams were monitored over one full season. Daily wellness questionnaires were completed each morning after waking throughout the season. GPS devices were worn during all training sessions to capture training outputs. Movement parameters assessed included total distance, total high-speed running distance, high speed running, player load, player load slow, maximal velocity, maximal velocity exposures, player load and player load slow. Additionally, session rating of perceived exertion (sRPE) was acquired following all training sessions. The author’s wanted to determine if well-being (Z-scores) impacted internal or external training parameters.
The results showed that perceptual measures did in fact affect training outputs. It was found that a reduced wellness Z-score of -1 related with a corresponded reductions in total high speed running distance (-3.5%), high speed running distance (-4.9%), maximal velocity sprinting (-3.1%), maximal velocity exposures (-4.6%), player load (-4.9%) and player load slow (-8.9%). Thus, it appears that when wellness markers are sufficiently disturbed, coaches can expect decrements in training outputs on the field. Therefore, wellness parameters may be useful not only in evaluating recovery status in athletes, but potentially for indicators of performance as well. This may enable coaches to modify training sessions on a daily basis according to team training responses.
Malone, S., Owen, A., Newton, M., Mendes, B., Tiernan, L., Hughes, B., & Collins, K. (2017). Wellbeing perception and the impact on external training output among elite soccer players. Journal of Science and Medicine in Sport.
The necessary recovery time between training sessions depends largely on the type and quantity of work that was performed. Other factors such as training history and familiarity of the training session also matter. Novel training stimuli tend to make athletes more sore, despite reasonably low load and volume. Therefore, coaches need to be cognizant of what type of training they’re prescribing and how it may affect recovery status. This is especially important when timing of the training session falls in close proximity to competition. Having athlete’s feeling sore and weak come game time is certainly undesirable. Therefore, coaches need to have a good grasp on how various forms of training impact recovery time.
A new study published ahead of print in the European Journal of Applied Physiology compared the physiological responses from high volume training and high intensity training in highly trained individuals. Twelve adult males with an average of 6 years of resistance training experience performed both a workout comprised of 8 sets of 3 repetitions with a heavy load (high intensity) or 8 sets of 10 repetitions with a moderate load (high volume) in a randomized, counter-balanced order. The performance markers measured were counter-movement jump peak power, maximal voluntary isometric contraction in the leg extension, isometric mid-thigh pull and isometric squat. Additionally, endocrine, inflammatory and muscle damage markers were also obtained. Performance and blood samples were taken at baseline and again 30 min, 24, 48 and 72 hours post-training.
The results showed that 30 mins following the high volume session, significantly greater reductions in performance markers including counter-movement jump peak power and isometric leg extension were observed compared to following the high intensity session. Maximal voluntary isometric strength remained suppressed below baseline for 72 hours following the high volume session but not following the high intensity session. Muscle damage markers were elevated following both protocols. Cortisol and inflammatory markers were significantly elevated following high volume training only at the 30 min time-point post-exercise. The authors conclude that high volume resistance training results in greater performance decrements than high intensity resistance training. This finding supports previous studies demonstrating prolonged performance decrements following hypertrophy training. Therefore, coaches should be careful when prescribing high volume training sessions within 72 hours of game day.
Bartolomei, S., Sadres, E., Church, D. D., Arroyo, E., Gordon III, J. A., Varanoske, A. N., … & Hoffman, J. R. (2017). Comparison of the recovery response from high-intensity and high-volume resistance exercise in trained men. European Journal of Applied Physiology, 1-12.
The pre-game meal might not receive the appropriate attention from coaches that it deserves. Many sports are held at times that are several hours after traditional meal times, e.g., 11 am or 4 pm. This often means that breakfast or lunch is the last meal that athletes eat before competition. For many coaches, meal emphasis has usually pertained to food selection to prevent athletes from feeling too heavy or drowsy before the game. Sticking with familiar foods so as not to cause any gastro-intestinal distress is certainly a good call. However, overall caloric content of meals may be getting overlooked or under-appreciated. Coaches tend to err on the side of having athletes eat less, but is this optimal? Sports like soccer and rugby that are continuous with high tempo require a tremendous amount of energy. Some researchers wonder if athletes are ingesting insufficient calories to meet energy demands on the field. Therefore, pre-game meals may be a useful intervention period to support competition performance.
A new study published ahead of print in the European Journal of Sports Science evaluated the effects of eating a pregame meal at the athletes habitual calorie content or at an increased caloric value on subsequent simulated match performance. A group of 7 English Academy Youth Premier League soccer players performed a 90-min soccer game simulation on two separate occasions. In a randomized order, the athletes ate their typical pre-game meal consisting of 260-270 kcal, roughly 135 minutes prior to the soccer session. On the other occasion, the athletes ate nearly double the amount of calories (~500 kcal). The meals were proportioned the same at both meals such that macronutrient distribution was ~60% carbohydrate, ~15% protein and ~25% fats. At the time of the simulated soccer match, all athletes were tested for countermovement jump, sprint speed, 30-m repeated sprint maintenance, perceived gut fullness, abdominal discomfort and soccer dribbling performance. Blood samples were acquired at rest, pre-exercise, half time and every 15 mins during training.
The results showed that dribbling precision and success were not different between conditions, but that mean dribbling speed was faster (4.3%) after the higher calorie breakfast. All other performance related tests were not significantly different between the diet interventions. Blood glucose and lactate concentrations were similar between conditions at each time-point. The athletes reported significantly increased feelings of gut fullness after the higher calorie meal without any significant increase in abdominal discomfort. The authors conclude that the larger calorie meal did not have any negative effects on performance and likely reduces the calorie deficit experienced during training after a lower calorie meal during training.
Briggs, M. A., Harper, L. D., McNamee, G., Cockburn, E., Rumbold, P. L., Stevenson, E. J., & Russell, M. (2017). The effects of an increased calorie breakfast consumed prior to simulated match-play in Academy soccer players. European Journal of Sport Science, 1-9.
Strength and conditioning coaches often fall into one of two camps when it comes to exercise selection for power development; those that are proponents of Olympic weightlifting and those that are not. The Olympic lifts tend to require greater proficiency in the skill of performing the movements. Thus, many individuals who oppose Olympic lifting think that too much time is wasted building technique while valuable training time that can involve greater loading with alternative movements is lost. Popular alternatives to Olympic lifts (and their derivatives) are jump-squats with a barbell or trap-bar. One can make the argument that jump-squats are easier to perform and thus can be implemented more easily with quicker progressions and thus illicit greater and faster improvements in power production.
A new study published ahead of print in the Journal of Strength and Conditioning Research compared the effects of using the hang high-pull or trap-bar jump-squat as the primary power exercise for enhancing lower-body power. A group of eight-teen (10 female, 8 male) division II collegiate swimmers with at least 1 year of resistance training experience volunteered as participants. The athletes were divided into a high-pull group and a squat-jump group. Thereafter, both groups performed a volume-equated 10-week periodized resistance training program. The loads were selected to optimize peak power outputs during the movements which corresponded to 70% of hang clean 1RM for the high-pull group and 20% of 1RM of the jump-squat group. Before and after the training program, all subjects were tested in the squat-jump, countermovement jump, and isometric mid-thigh pull. Measures of height, power and rate of force development were calculated from force plate analysis.
Post-testing revealed that both training groups significantly improved in each of the performance markers. However, no significant differences were observed between groups. While between group differences did not reach statistical significance, effect sizes (representing the magnitude of the difference) ranged from small to moderate in favor of the jump squat group for squat-jump height and peak power as well as relative peak force and peak rate of force development in the isometric mid-thigh pull. Therefore, it appears that both training interventions can significantly improve indices of power in college swimmers, but the jump-squat group made small to moderately greater improvements than the high-pull group in several parameters.
Oranchuk, DJ., et al. Comparison of the Hang High-Pull and Loaded Jump Squat for the Development of Vertical Jump and Isometric Force-Time Characteristics. Journal of Strength and Conditioning Research, In press.
Traditionally, most coaches have emphasized development of vertical force production for enhancing sprinting speed. However, with accumulating new research, coaches are becoming increasingly aware of the important contribution that horizontal force production plays in sprinting speed. However, resistance training to enhance force production is often approached with the primary use of bilateral exercises. Some researchers hypothesize that asymmetry in horizontal force production among lower limbs may limit maximal sprinting speed and potentially increase injury risk among athletes. Thus, identifying asymmetries and making interventions to strengthen the weaker limb may improve sprinting speed.
A new single-subject case study published ahead of print in the International Journal of Sports Physiology and Performance investigated the effects of reducing lower limb horizontal force asymmetry on markers of sprint performance in an adult male team-sport athlete. Unilateral horizontal force, peak velocity and peak power were measured periodically on a non-motorized treadmill throughout a 6-week control-block of testing. A subsequent 6-week training intervention was then used to strengthen the weaker limb and reduce asymmetry between limbs. A combination of unilateral exercises and plyometrics were used to improve strength and power in the weaker limb with an emphasis on horizontal force. Bilateral work was also implemented though no unilateral work was performed for the stronger limb. Symmetry and sprint performance markers were then re-evaluated following the 6-week intervention.
The results showed that the training program reduced lower limb horizontal force asymmetry by 19% (moderate effect size). In addition, maximal velocity sprinting speed also meaningfully improved by 2% (moderate effect size). Finally maximal power production substantially improved by 15% (very large effect size). The authors conclude that this case example provides support for targeted training programs that aim to decrease horizontal force asymmetry in athletes for improving sprint performance. Certainly, more research is needed with larger samples to further evaluate the effectiveness of this strategy for improving performance and reducing injury risk.
Brown, S. R., Feldman, E. R., Cross, M. R., Helms, E. R., Marrier, B., Samozino, P., & Morin, J. B. (2017). The Potential for a Targeted Strength Training Programme to Decrease Asymmetry and Increase Performance: A Proof-of-Concept in Sprinting. International Journal of Sports Physiology and Performance, 1-13.
Olympic weightlifters often use cluster training for developing maximal strength and power. Cluster sets involve intermittent rest periods (~30 seconds) between repetitions. For example, a set of 6 repetitions can be performed in a cluster configuration by performing repetitions 1 and 2, rest for 30 seconds, performing repetitions 3 and 4, rest for 30 seconds, then finish the remaining 2 repetitions. In contrast, a traditional straight set would involve performing all 6 repetitions with no rest periods. The cluster configuration is thought to lead to superior improvements in power adaptations by enabling a higher power output for each repetition, even towards the end of the set. With a traditional straight set, power tends to progressively decline as fatigue accumulates and ATP-PC stores diminish. Thus, cluster sets may be useful for athletes when the aim is to develop maximal power.
A new study published ahead of print in the Journal of Strength and Conditioning Research compared the effects of a traditional set versus cluster set training intervention for enhancing lower body power output. A group of 19 college-aged males were randomly divided into a traditional set group (6 sets of 6 reps with 20% of 1RM) and a cluster set group (6 sets of 6 reps with 30 seconds rest between every 2 reps with 20% of 1RM) featuring the barbell jump-squat. Both groups trained twice per week for three consecutive weeks. Preceding the power training intervention, both groups performed an 8-week periodized training program progressing from weeks of circuit training to hypertrophy training and finishing with strength training. Before and after the intervention, velocity outputs during squat jumps with 25%, 50% and 75% of 1RM were quantified via force plate.
The results showed that the cluster training group experienced a significant increase in jump-squat velocity at 25% 1RM. This increase was significantly greater than that observed in the traditional set group (effect size = moderate). Apart from this, no other significant differences were observed for jump-squat velocity at 50% and 75% of 1RM. These results are likely due to the fact that the power training phase exclusively involved loads at 20% of 1RM. Therefore, the adaptations were specific to the imposed training demands. This considered, it appears that cluster training is superior to traditional straight set training for improving velocity at a specific load. Therefore, coaches should consider prescribing cluster configurations during power development phases.
Morales-Artacho, AJ. Influence Of A Cluster Set Configuration On The Adaptations To Short-Term Power Training. Journal of Strength and Conditioning Research, In Press.