The impact of short duration, high intensity exercise on cardiac troponin release

The aim of this study was to assess the appearance of cardiac troponins (cTnI and/or cTnT) after a short bout (30 s) of ‘all-out’ intense exercise and to determine the stability of any exercise-related cTnI release in response to repeated bouts of high intensity exercise separated by 7 days recovery. Eighteen apparently healthy, physically active, male university students completed two all-out 30 s cycle sprint, separated by 7 days. cTnI, blood lactate and catecholamine concentrations were measured before, immediately after and 24 h after each bout. Cycle performance, heart rate and blood pressure responses to exercise were also recorded. Cycle performance was modestly elevated in the second trial [6·5% increase in peak power output (PPO)]; there was no difference in the cardiovascular, lactate or catecholamine response to the two cycle trials. cTnI was not significantly elevated from baseline through recovery (Trial 1: 0·06 ± 0·04 ng ml−1, 0·05 ± 0·04 ng ml−1, 0·03 ± 0·02 ng ml−1; Trial 2: 0·02 ± 0·04 ng ml−1, 0·04 ± 0·03 ng ml−1, 0·05 ± 0·06 ng ml−1) in either trial. Very small within subject changes were not significantly correlated between the two trials (r = 0·06; P>0·05). Subsequently, short duration, high intensity exercise does not elicit a clinically relevant response in cTnI and any small alterations likely reflect the underlying biological variability of cTnI measurement within the participants.

Role of active and passive recovery in adaptations to high intensity training

It has been established that Wingate-based high-intensity training (HIT) consisting of 4 to 6 x 30-s all-out sprints interspersed with 4-min recovery is an effective training paradigm. Despite the increased utilisation of Wingate-based HIT to bring about training adaptations, the majority of previous studies have been conducted over a relatively short timeframe (2 to 6 weeks). However, activity during recovery period, intervention duration or sprint length have been overlooked. In study 1, the dose response of recovery intensity on performance during typical Wingate-based HIT (4 x 30-s cycle all-out sprints separated by 4-min recovery) was examined and active recovery (cycling at 20 to 40% of V̇O2peak) has been shown to improve sprint performance with successive sprints by 6 to 12% compared to passive recovery (remained still), while increasing aerobic contribution to sprint performance by ~15%. In the following study, 5 to 7% greater endurance performance adaptations were achieved with active recovery (40%V̇O2peak) following 2 weeks of Wingate-based HIT. In the final study, shorter sprint protocol (4 to 6 x 15-s sprints interspersed with 2 min of recovery) has been shown to be as effective as typical 30-s Wingate-based HIT in improving cardiorespiratory function and endurance performance over 9 weeks with the improvements in V̇O2peak being completed within 3 weeks, whereas exercise capacity (time to exhaustion) being increased throughout 9 weeks. In conclusion, the studies demonstrate that active recovery at 40% V̇O2peak significantly enhances endurance adaptations to HIT. Further, the duration of the sprint does not seem to be a driving factor in the magnitude of change with 15 sec sprints providing similar adaptations to 30 sec sprints. Taken together, this suggests that the arrangement of recovery mode should be considered to ensure maximal adaptation to HIT, and the practicality of the training would be enhanced via the reduction in sprint duration without diminishing overall training adaptations.

An elevated systolic blood pressure response at 8 minutes in full contact exercise may identify hypertensive subjects

The aim of this study was to identify hypertension (HT) in karate competitors (KCs) in high intensity exercise. Values were compared with an exercise control group (EC). The 84 subjects were randomly divided into two groups: KC and EC. Resting blood pressure (BP) was measured the day before and immediately precompetition. A further three measurements were taken postexercise for all subjects at 1-, 2-, and 8- minute intervals. At rest, day one, mean BP of KC was 134/84 ± 3/2 mmHg vs. EC, 124/72 ± 1/2 mmHg and on day 2, was 141/79 ± 3/2 mmHg vs. EC, 125/72 ± 1/2 mmHg, respectively. Eight minutes postcompetition, BP of KCs was 140/77 ± 2/1 mmHg vs. EC 135/75 ± 2/1 mmHg. High blood pressure (HBP) was recorded in 60.5% of KCs on day 2, and essential HT that required medical therapy was subsequently diagnosed in 5% of KCs. Five percent of EC also had HBP, but subsequent medical examination reported normal values.

Considerations in the use of high intensity leg cycle ergometry as a test of muscular performance

High intensity leg cycle ergometry is a widely used method of measuring muscular performance during maximal exercise. Until recently, it was deemed to be a predominantly lower body activity; however, there is now evidence to suggest that the upper body could be making a significant contribution to power output, as demonstrated by the intense electrical activity of the forearm musculature. As high intensity cycle ergometry often is used to measure performance in untrained cyclists it is important they are given at least two familiarisation trials to ensure results are both reliable and reproducible. In addition, diurnal variations exist during a single high intensity bout of exercise. It is likely these daily fluctuations are influenced by a number of biochemical and physiological variables. The purpose of this article is to outline factors that contribute to our interpretation of data following high intensity cycle ergometry.

Effects of a 12-week aerobic exercise intervention on eating behaviour, food cravings and 7-day energy intake and energy expenditure in inactive men

This study examined effects of 12 weeks of moderate-intensity aerobic exercise on eating behaviour, food cravings and weekly energy intake and expenditure in inactive men. Eleven healthy men (mean ± SD: age, 26 ± 5 years; body mass index, 24.6 ± 3.8 kg/m2; maximum oxygen uptake, 43.1 ± 7.4 mL/kg/min) completed the 12-week supervised exercise programme. Body composition, health markers (e.g. blood pressure), eating behaviour, food cravings and weekly energy intake and expenditure were assessed before and after the exercise intervention. There were no intervention effects on weekly free-living energy intake (p=0.326, d=-0.12) and expenditure (p=0.799, d=0.04), or uncontrolled eating and emotional eating scores (p>0.05). However, there was a trend with a medium effect size (p=0.058, d=0.68) for cognitive restraint to be greater after the exercise intervention. Total food cravings (p=0.009, d=-1.19) and specific cravings of high-fat foods (p=0.023, d=-0.90), fast-food fats (p=0.009, d=-0.71) and carbohydrates/starches (p=0.009, d=-0.56) decreased from baseline to 12 weeks. Moreover, there was a trend with a large effect size for cravings of sweets (p=0.052, d=-0.86) to be lower after the exercise intervention. In summary, 12 weeks of moderate-intensity aerobic exercise reduced food cravings and increased cognitive restraint, however, these were not accompanied by changes in other eating behaviours and weekly energy intake and expenditure. The results indicate the importance of exercising for health improvements even when reductions in body mass are modest.