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What the experts say

Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology, and athletic development.

Mind over injury

Physical factors involved in injury prevention are becoming increasingly well characterized as the process of fitness improvement, and skills development becomes better understood. A recent paper[1], however, looked at the prediction and prevention of injury from a psychological approach and found from a study of 470 rugby players that social support; coping, and the previous injury all interacted to maximize the effect of life stress and injury. The second part of the study looked at stress management strategies as an intervention for reducing injury among players identified in the first part as having an at-risk psychological profile for injury - numbering 48 in total. The experiment ran for a whole season with half of this number randomly assigned to a control group. The outcome from those in the intervention group was a significant reduction in lost time due to injury and a reduction in worry.

Time of training relates to the time of performance

Researchers[2] looked at the effect of time of training on the time of competition by preparing a group of 8 cyclists in two different ways for a 16.1km time trial started at 07:00hrs. In time trial 1 the cyclists underwent a 30min sub-maximal session at 60% VO2 peak at 07:00hrs and in time trial 2 at 12:00hrs the day before separate time trials. The outcome was that time trial 1 was completed in 1672+/- 135s while time trial 2 was in 1706 +/- 159s (a difference of around 300s). The physical/physiological data from the quicker time trials following the 07:00 previous day preparation outing showed elevated work rates, lactate accumulation, and heart rate relative to the time trial completed after the 12:00hrs previous day outing. These data suggest that performing an exercise at the same time in the day(s) before competition benefits the cyclist. Only one point appears unclear from the paper to the recovery period following the 12:00hrs outing - this was 18.5hrs rather than 23.5 hrs before the 07:00 time trial. Could the shorter recovery have been a contributing factor to the slower time trial?

Cycling is best for anaerobic capacity assessment

Comparing and contrasting the effectiveness of laboratory measurements provides potentially useful information. A study[3] that compared treadmill running to cycle ergometry for estimations of anaerobic capacity (AC) was based on the examination of 10 untrained, 10 aerobic-trained, and 10 anaerobic-trained (400m sprinters). The tests comprised measurement of VO2 max, individual aerobic threshold (IAT) to determine aerobic power, and finally, from a series of sprints at increasing speeds, the work output was calculated. The results indicated absolute values of AC below those measured by cycle ergometry, and it was proposed that a factor not taken into account was the horizontal work done while running on a treadmill. Also, a factor could be the duration of each sprint test. Finally, the critical velocity (max speed attainable for a long time) was higher than the IAT which must lead to an underestimation of the AC value. The treadmill test allowed for differentiation between the groups but did not assign correct AC values.

Men and women are different!

An interesting paper[4] continued the theme that was raised last month on different responses to exercise between male and female athletes. The study used two different running tests - firstly - graded exercise to exhaustion to determine maximal aerobic flow, the velocity at lactate threshold and velocity at the halfway point (delta 50) between these two measures, and secondly - a constant all-out run at the delta 50 to determine the time to exhaustion at this intensity. 8 male and 8 female middle-distance endurance-trained athletes participated in the tests. The outcome was that the female athletes all perceived exercise as being harder felt they could endure less and had higher heart rate values than males for a given absolute velocity. In contrast, there were no differences for a given relative velocity. (This only seems to demonstrate that the men in the study were faster runners, on average, than the women and were, therefore, more comfortable at the same absolute velocity but that there was no difference at velocities matched relative to their maximum). Interestingly female athletes perceived exercise as lighter and felt that they could endure more than the males for a given absolute time. In contrast, at a percentage time relative to the final time of exhaustion, there was no difference.

Aerobics energy system

Several papers have been reviewed in general physiology concerning oxygen consumption and recovery. The first[5] looked at a group of competitive collegiate level footballers and the impact of pre-season training and in-season adaptations based on the Wingate test and other appropriate measurements before and during the season. The authors conclude that no change in power performance measures was observed at any time whereas the extent of muscle de-oxygenation between the start of the season and 11 weeks into the season was measurably reduced during intense exercise and that oxygen recovery kinetics improve dramatically during the competitive season - meaning shorter rest spells were necessary. A further paper[6] based on a study of cyclists indicates that this type of improvement may be largely attributable to adaptations in the peripheral circuit rather than to central adaptations following intensive exercise bouts in well-trained endurance athletes. To help identify appropriate test measurements to support such aerobic development a paper[7] found that in general sub-maximal indices of aerobic fitness including oxygen uptake and power output are more useful measures of actual cycling performance than VO2 max and peak power output.

Recovery and fatigue in power workouts

Moving away from exercise, predominantly involving the aerobic energy system researchers have looked at factors affecting fatigue and the recovery of power[8]. The study used a group of 13 men performing isotonic knee extensions at the fastest rate they could until velocity reduced by 35%. During this time (ca. 38s) power was reduced by 42% and maximum voluntary contraction (MVC) by 26%. Power recovered by 5 minutes whereas MVC only recovered to 85% of the baseline even after 10 minutes of rest. Peripheral factors were again concluded to be the limiting factor. The implication of this information on planning a power training session is interesting since although potentially useful power work can be performed maximally after 5 minutes of recovery, the ability to express MVC will be depressed for longer.

Shoe technology better than nature?

One or two middle distance and endurance runners spring to mind when barefoot running is mentioned. A recent study[9] looked at the mechanical comparison of barefoot versus shoe running. The primary findings based on a study of 35 subjects running for 4 minutes at 3.33m/s (or around 8 minutes/mile) were that barefoot running reduces contact and flight time as well as attenuates impact peak force. Barefoot running at this pace also leads to higher breaking forces and pushing impulses - perhaps not as energy-efficient at this pace as when running in suitable running shoes.

Nutrition cornucopia

Fuelling the system is critical to support all long-term training. So a study of eating disorders and risk factors in 283 elite Spanish female athletes[10] provides handy and meaningful information. Taken from 20 different sports, the athletes were questioned with various well-accepted methods to establish that the proportion suffering from some form of eating disorder was 5-times that of the general population. Key factors identified included exposure to body form in public as a general factor, and specifically, pressure from coaches seems to be a risk factor for bulimia.

Looking at an array of recent papers on specific dietary components or supplements revealed a whole series of interesting evidence: The first paper[11] sought to establish a relationship between controlled caffeine consumption at different levels and hydration levels on the basis that caffeine is touted as a diuretic that may impair performance. The study could find no evidence that caffeine acts chronically as a diuretic.

The next[12] looked at glucose feeding during endurance cycling. It confirmed that over a 75-minute ride at 80% VO2 max that glucose ingestion during exercise can spare endogenous protein and carbohydrate, in fed cyclists, without glycogen depletion. This would allow the cyclist to continue for longer at this intensity.

Vitamin C supplementation[13] was shown to attenuate exercise-induced protein oxidation in a manner proportional to dose. Sparing protein oxidation may be beneficial to endurance athletes - the truth behind the legend as to why some East African endurance athletes are believed to consume large quantities of oranges before training bouts and why oranges are also a favourite half-time food for soccer players?

Specific supplementation with L-carnitine receives a massive promotion in the gym environment, promising to do everything for you except for your training sessions. Much of its claimed physiological benefit seems to centre on the enhancement of fat burning. A recent paper[14] that looked at combining L-carnitine with L-tartrate found no impact on fat burning whatsoever but did appear to increase carbohydrate oxidation in males but not significantly in females. I guess you have to make your mind up as to whom and what you believe!

Amino acids - vital to life and performance

Finally, two massively informative review papers have appeared from different groups looking at dietary supplementation with minerals and their effect on sports performance[15] and a second on nutrient administration and resistance training[16]. In this issue, we will focus on the latter and cover the former next month. Resistance training acts to improve hypertrophy (build muscle) and increase muscle strength and with correct practice, enhance power and explosivity. The study has reviewed the literature with a clear emphasis on amino acid supplementation and has produced a proposal for a series of guidelines as follows:

  • Resistance training modestly stimulates protein synthesis and further stimulates protein breakdown resulting in an overall negative protein balance after exercise
  • As the training status of an individual progresses, the magnitude of changes seen in protein synthesis and breakdown diminishes after each exercise bout as well as a diminished increase of protein synthesis after each subsequent exercise bout
  • Infusion or ingestion of amino acids is an effective way to increase amino acid concentrations at rest or after resistance exercise
  • Availability of amino acids after resistance exercise increases protein synthesis
  • Essential amino acids do appear to play a primary role in protein synthesis and adding carbohydrates to them may enhance this effect
  • Ingestion of carbohydrates alone after resistance exercise causes marginal improvements in overall protein synthesis while maintaining a negative net protein balance. No studies have found carbohydrates to be detrimental, and they may be useful to enhance palatability; however, the additional caloric burden may not be desired
  • A small dose of essential amino acids after resistance exercise has been found to stimulate protein synthesis to a similar degree when compared to studies that used much larger doses of both amino acids (EAA, NEAA, or both) or that were combined with carbohydrate
  • Ingestion of amino acids after resistance exercise has been shown at many different time points in several studies to stimulate increases muscle protein synthesis, time points in several studies to stimulate increases in muscle protein synthesis, cause minimal changes in protein breakdown, and increase overall protein balance. It has not been conclusively determined what time point is optimal. Similar changes have been found for studies that have administered amino acids alone or with carbohydrates immediately upon completion of an acute exercise bout, 1 hour after completion, 2 hours after completion, and 3 hours after completion. Interestingly, ingesting nutrients before the exercise bout may have the most benefit of all the time points
  • It is possible for the mechanisms involving amino acid transport and protein synthesis to be overwhelmed with extremely high, continuous levels of amino acids. The likelihood of this occurring is rare even considering the highest protein intakes among individuals
  • An optimal dosage in which to ingest amino acids at this time does not exist. Studies using similar techniques while resistance training has used 6g EAA only, 6g EAA + 6g NEAA, 12g EAA only, 17.5g whey protein, 20g casein protein, 20g whey protein, 40g mixed amino acid, 40g EAA only all with similar increases in protein synthesis and protein balance. Athletes who desire to increase muscle mass or are involved in power sports should consider consuming protein supplements that will provide amino acids in similar amounts used in these studies
  • Intact proteins or combinations of them that are used in popular protein supplements appear to elicit similar increases in protein balance after resistance training as compared to other studies using free amino acids.

From these primary findings, it is hoped that athletes, coaches, nutritionists, and researchers will be able to provide clearer advice and recommendations when consulting themselves, their players, clients, or research participants regarding the optimal administration of nutrients while participating in a resistance training program.

Article Reference

This article first appeared in:

  • HETHERINGTON, N. (2005) What the experts say. Brian Mackenzie's Successful Coaching, (ISSN 1745-7513/ 27 / November), p. 12-14

References

  1. Maddison R and Prapavessis H 'A Psychological Approach to the Prediction and Prevention of Athletic Injury' JSEP, 27(3), September 2005
  2. Edwards BJ et al. 'Can Cycling Performance in an Early Morning, Laboratory-Based Cycle Time-Trial be Improved by Morning Exercise the Day Before?' Int J Sports Med 2005; 26: 651-656
  3. Striegel H et al. 'Determining Anaerobic Capacity Using Treadmill Ergometry' Int J Sports Med 2005; 26: 563-568
  4. Garcin et al. 'Sex-Related Differences in Ratings of Perceived Exertion and Estimated Time Limit' Int J Sports Med 2005; 26: 675-681
  5. Hoffman et al. 'The Effect of a Competitive Collegiate Football Season on Power Performance and Muscle Oxygen Recovery Kinetics' The Journal of Strength and Conditioning Research: Vol. 19, No. 3, pp. 509-513
  6. Laursen PB et al. 'Influence of High-Intensity Interval Training on Adaptations in Well-Trained Cyclists' The Journal of Strength and Conditioning Research: Vol. 19, No. 3, pp. 527-533
  7. Impellizzeri FM et al. 'Correlations between physiological variables and performance in high level cross country off road cyclists' British Journal of Sports Medicine 2005;39:747-751
  8. Cheng AJ and Rice CI 'Fatigue and recovery of power and isometric torque following isotonic knee extensions' J Appl Physiol 99: 1446-1452, 2005
  9. Divert C et al. 'Mechanical Comparison of Barefoot and Shod Running' Int J Sports Med 2005; 26: 593-598
  10. Toro J et al. 'Eating Disorders in Spanish Female Athletes' Int J Sports Med 2005; 26: 693-700
  11. Armstrong LE et al. 'Fluid, Electrolyte, and Renal Indices of Hydration During 11 Days of Controlled Caffeine Consumption' IJSNEM, 15(3), June 2005
  12. van Hamont D 'Reduction in Muscle Glycogen and Protein Utilization with Glucose Feeding During Exercise' IJSNEM, 15(4), August 2005
  13. Goldfarb AH et al. 'Vitamin C Supplementation Affects Oxidative-Stress Blood Markers in Response to a 30-Minute Run at 75% VO2 max' IJSNEM, 15(3), June 2005
  14. Abramowicz WN et al. 'Effects of Acute Versus Chronic L-Carnitine L-tartrate Supplementation on Metabolic Responses to Steady State Exercise in Males and Females' IJSNEM, 15(4), August 2005
  15. Williams MH 'Dietary Supplements and Sports Performance: Minerals' Journal of the International Society of Sports Nutrition 2(1):43-49, 2005.
  16. Kerksick CM and Leutholtz B 'Nutrient Administration and Resistance Training' Journal of the International Society of Sports Nutrition 2(1):50-67, 2005

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • HETHERINGTON, N. (2005) What the experts say [WWW] Available from: https://www.brianmac.co.uk/articles/scni27a7.htm [Accessed

About the Author

Nigel Hetherington was 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 British Athletics level 4 performance coach in all events he has coached athletes to National and International honours in sprints, and hurdles as well as a World Record holder in the Paralympic shot. He has 10 years of experience as a senior coach educator and assessor trainer on behalf of British Athletics. Nigel is also an experienced athlete in the 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 of experience in scientific research and publishing.