What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology and athletic development.
One of the challenges of coaching with regards to athletes taking part in competition in variable climatic conditions is the question of how, or indeed if, the warm up should be altered? Many teams and individuals have a preset warm-up routine appropriate only to the 'average' conditions in which they prepare for training or competition. Often, a fallback plan is missing which allows for variations in climate and levels of excitement of the athletes. A stud aimed to examine whether athletes are able to self-select their optimal warm up and proposed a methodological approach to investigating the effects of warm up on performance. In the study male subjects underwent a free field warm up at a self-selected intensity and duration during which heart rate and body temperature were monitored. The intensity of this warm up was subsequently estimated from the heart rate obtained during an incremental test to determine maximal power. Performance (cycle time to exhaustion at maximal power), heart rate and temperature, were then examined following each of: no warm up; reference warm up (based on free warm up); reference-10% intensity and reference+10% intensity. Results showed no significant difference in heart rate and temperature increase between free and reference warm up. Most importantly, performance improvement after warm up conditions gave reference (56%) > reference-10 (33%) > reference+10 (11%) > no warm up. It was interesting that the higher intensity warm up of reference+10 led to a reduction in performance relative to even the reduced warm up of reference-10 - you can definitely overdo the warm up! A warm up intensity ranging from 54-72% of maximal power and inducing an increase in heart rate to around 80% max, was found to be optimal. While most athletes were able to self-determine the intensity of their optimal warm up, for others there is still a need for continued coaching intervention.
A study compared player agility, when responding to a life-size, interactive video display of a netball player initiating a pass to a traditional, pre-planned agility movement where no external stimulus was present for the measurement of agility in highly, moderately and lesser skilled netball players. The total movement times and decision times of the players were the primary dependent measures of interest. Results revealed significant differences existed between the two test conditions demonstrating that they were measuring different types of agility. The highly skilled group was significantly faster in both the reactive and planned test conditions relative to the lesser skilled group, while the moderately skilled group was significantly faster than the lesser skilled group in the reactive test condition. The decision time component within the reactive test condition revealed that the highly-skilled players made significantly faster decisions than the lesser skilled players. It is reasoned that it is this decision making component of reactive agility that contributes to the significant differences between the two test conditions. Indeed this is clearly what sets the two different types of players apart! Fatigue can have an effect on performance on sport-specific skills. A study investigated the effect of moderate and high intensity total body fatigue on passing accuracy in expert and novice basketball players. Ten novice basketball players and ten expert basketball players all aged around 23 years performed the modified AAHPERD Basketball Passing Test under three different testing conditions: rest, moderate intensity and high intensity total body fatigue.
Fatigue intensity was established using a percentage of the maximal number of squat thrusts performed by the participant in one minute. The results showed that following high intensity total body fatigue there was a significant detriment in the passing performance of both novice and expert basketball players when compared to their resting scores. Fundamentally however, the detrimental impact of fatigue on passing performance is not as steep in the expert players compared to the novice players. The results suggest that expert or skilled players are better able to cope with both moderate and high intensity fatigue conditions and maintain a higher level of performance when compared to novice players. The findings of this research therefore, suggest the need for trainers and conditioning coaches in basketball to include moderate, but particularly high intensity exercise into their skills sessions. This specific training may enable players at all levels of the game to better cope with the demands of the game on court and maintain a higher standard of play. Basically, this fully supports the stages of learning model for skill acquisition. A robust skill WILL hold up better under fatigue.
An earlier study showed that six sessions of sprint interval training (SIT) over 2 weeks increased cycle endurance capacity. A follow-up study showed that short-term SIT impacts on the metabolic pathway to reduce skeletal muscle glycogenolysis and lactate accumulation during exercise and increases the capacity for pyruvate oxidation in the mitochondria. Eight men performed six sessions of 4-7 x 30-s "all-out" cycling with 4 minutes of recovery over a two-week period. Subjects also performed a 250-kJ time trial before and after SIT to assess changes in cycling performance. SIT increased muscle glycogen content by 50%. Pyruvate oxidation was higher after training and net muscle glycogenolysis and lactate accumulation during exercise were reduced. Time trial performance improved by 9.6% after training while the control group showed no change in performance when tested two-weeks apart without SIT. The authors concluded that short-term SIT improved cycling time trial performance and resulted in a closer matching of glycogenolytic flux and pyruvate oxidation during submaximal exercise.
Recent research examined which style of jump performance related best to sprint acceleration performance from a block start. Ten competing male track sprinters (100m personal best 10.37-11.42s) performed 10m sprints from blocks. Squat jump (SJ), countermovement jump (CMJ), continuous straight legged jump (SLJ), single leg hop for distance, and single leg triple hop for distance measures of power were also tested. Statistical analysis identified CMJ average power (W/kg) as a predictor of 10m-sprint performance from a block start. CMJ force and power and SJ power generating capabilities also showed a strong relation to sprint performance. Putting this into perspective, a 3% increase in CMJ average power resulted in an improvement of 0.01s (0.5%) in 10m sprint performance. Further, a 3.5% increase in SJ average power was predicted to result in a 0.01 s (0.5%) reduction in 10m sprint time. The results of this study seem to suggest that the ability to generate power both elastically during a CMJ and concentrically during a SJ to be good indicators of sprint performance over 10m from blocks. Now, the real challenge is to turn this one around and identify which, if any, of these jumping activities can facilitate improvement in sprinting performance!?
In a comparison between male and female steeplechasers a study investigated three aspects of hurdling technique: 1) Differences in the ratio of the landing step to the penultimate step around each steeplechase barrier (excluding the water jump), 2) differences in step lengths between regular barriers, and 3) changes in the step lengths around the barrier throughout the race. The stride lengths around the 28 regular barriers of the top seven men and women at the 2003 USA Track and Field Championships were measured using a two-dimensional analysis. The study found that men exhibited a smaller ratio between the lengths of the landing to penultimate steps than women. No step length differences were observed between the four barriers in the step lengths around each barrier. Athletes gradually increased the total length of all steps in the region of the barriers throughout the race. A smaller ratio between landing to penultimate stride lengths showed that the barriers affect women less than men. There may be a need to train men and women differently for regular barriers in the steeplechase and / or to slightly alter racing strategy.
A study examined relative energy system dependency (via type substrate use) during exercise in young athletes from early-pubertal (EP), mid-pubertal (MP), late-pubertal (LP), and young-adult (YA) males. Fuel use was calculated during cycling exercise at 30 to 70% of VO2peak. Significant group by intensity interactions were found for lactate, RER, percent CHO, and fat use, in addition to fat and CHO oxidation rates, which suggest a maturation effect on substrate use during exercise. While not statistically significant at all intensities, analyses revealed greater fat use, lower CHO use, and lower lactate concentrations in EP and MP compared to LP or YA. No differences were noted between EP and MP or LP and YA at any intensity, suggesting the development of an adult-like metabolic profile occurs between mid- to late-puberty and is complete by the end of puberty. This information confirms the widely held belief that young athletes need to be trained differently to mature adults because their energy system development is incomplete from a fundamental biochemical perspective.
In a study 15 subjects (3 women, 12 men) participated in 3 trials to assess whether body cooling between 2 bouts of exercise in the heat enhances performance during the second exercise session. Subjects ran 90 minutes on hilly trails in a hot environment (approximately 27°C) before 12 minutes of either cold-water immersion (CWI; 13.98°C), ice water immersion (IWI; 5.23°C), or a mock treatment (MT) of sitting in a tub with no water (29.50°C). After immersion, subjects ran a 2-mile race. CWI had faster performance time (725 seconds) than MT (769 seconds). CWI and IWI had significantly lower rectal temperatures post immersion than MT as well as post-race. Heart rate also remained significantly lower during the CWI and IWI trials for the first half of the race. In conclusion, CWI enhances performance (6% improvement in race time) in the second bout of exercise, supporting its potential role as an ergogenic aid in athletic performance
The effect of active versus passive recovery on blood pH (level of acidosis) was studied during multiple bouts of intense exercise. Ten males completed two exercise trials consisting of three exercise bouts to exhaustion with either a 12-minute active (20% workload max) or passive recovery between bouts. Blood pH was slightly lower in the passive (p) recovery group compared to active (a) group throughout the second and third recovery periods. Exercise performance times did not differ between recovery conditions. No difference was found between conditions for blood pH recovery kinetics (slope and half-time to recovery). Subsequent performance during multiple bouts of intense exercise to exhaustion may not be influenced by blood acidosis or mode of recovery. The study showed that three exercise bouts could be completed satisfactorily with the rest interval specified. The effect of further exercise bouts was not reported. The study appears to oppose training guidelines with regard to, for example, lactate recovery between bouts of intense exercise where active recovery is encouraged. However, blood pH may not be the only marker here and local muscle pH conditions may need to be taken account of especially where higher numbers of exercise bouts are included.
A study investigated if vitamin C supplementation before and after eccentric exercise could reduce muscle soreness (MS) and improve muscle function. Eighteen healthy men randomly assigned to a dosing of 3g / day of either a placebo (P) or vitamin C (VC) treatment group for 2 weeks prior to and 4 days after performing 70 eccentric elbow extensions with their non-dominant arm. MS increased in both groups with significantly reduced MS for the first 24 hours with VC. Range of motion was reduced equally in both groups after the exercise. Muscle force declined equally and was unaffected by treatment. VC attenuated the creatine kinase (CK - associated with muscle damage) increase at 48 hours after exercise with similar CK after this time. These data suggest that vitamin C pretreatment can reduce MS and delay CK increase but has no effect on muscle function loss. A further paper delved deeper into CK presence by examining four differing recovery interventions on the rate of muscle damage recovery. 23 elite male rugby players were monitored before, immediately after, 36 hours after, and 84 hours after competitive rugby matches. Players were randomly assigned to complete one of four post-match strategies: contrast water therapy (CWT), compression garment (GAR), low intensity active exercise (ACT), and passive recovery (PAS). The results showed significant increases in CK activity as a result of the rugby match. The magnitude of recovery in the PAS intervention was significantly worse than in the ACT, CWT, and GAR interventions at the 36 and 84 hour time points. In conclusion low impact exercise immediately post-competition, wearing compression garments, or carrying out contrast water therapy enhanced CK clearance more than passive recovery in young male athletes.
In a paper nine male, endurance-trained cyclists performed an interval workout followed by 4 hours of recovery, and a subsequent endurance trial to exhaustion at 70% VO2max, on three separate days. Immediately following the first exercise bout and 2 hours of recovery, subjects drank isovolumic amounts of chocolate milk (CM), fluid replacement drink (FR) or carbohydrate replacement drink (CR). Carbohydrate content was equivalent for CM and CR. Time to exhaustion (TTE), average heart rate (HR), rating of perceived exertion (RPE), and total work (WT) for the endurance exercise were compared between trials. TTE and WT were significantly greater for CM and FR trials compared to CR trial. The results of this study suggest that chocolate milk is an effective recovery aid between two exhausting exercise bouts.
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About the Author
Nigel Hetherington is the Head Track & Field Coach at the internationally acclaimed Singapore Sports School. He is a former National Performance Development Manager for Scottish Athletics and National Sprints Coach for Wales. Qualified and highly active as a UK Athletics (UKA) level 4 performance coach in all events he has coached athletes to National and International honours in sprints, hurdles as well as a World Record holder in the Paralympic shot. He has 10 years experience as senior coach educator and assessor trainer on behalf of UKA. Nigel is also an experienced athlete in sprint (World Masters Championship level) and endurance (3-hour marathon runner plus completed the 24 hour 'Bob Graham Round' ultra-endurance event up and down 42 mountain peaks in the English Lake District). He is a chartered chemist with 26 years' experience in scientific research and publishing.
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