Cortisol, DHEA, performance and training in elite swimmers

Salivary cortisol (C) and DHEA concentrations were measured in 9 elite swimmers (4 female and 5 male) over a 37-week period, 5 to 12 times per swimmer, before 68 competitions. For female and male swimmers, no significant relationship was found between C, DHEA and performance. For the whole group, C was negatively correlated with week number of training (r = -0.31, p < 0.01). The incorporation of the cumulated distance swum as a second variable in the regression increased r to 0.56 (p < 0.01). The higher the cumulated distance swum, the higher C. No significant relationship was found between DHEA and distance swum. For individual swimmers, 3 of 4 females showed a significant negative relationship between C and cumulated dry-land training. No equivalent relationship was found for DHEA. The 2 males practicing dry-land training showed a significant and negative relationship between DHEA and cumulated dry-land training. No equivalent relationship was found for C. Thus, C and DHEA were not good predictors of swimming performance. C for individual females, and DHEA for individual males were considered useful markers for dry-land training stress.

Temporal aspects of the VO2 response at the power output associated with VO2peak in well trained cyclists: Implications for interval training prescription

The power output achieved at peak oxygen consumption (VO2 peak) and the time this power can be maintained (i.e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the VO2 response to exercise at the cycling power that output well trained cyclists achieve their VO2 peak (i.e., Pmax). Following a progressive exercise test to determine VO2 peak, 43 well trained male cyclists (M age = 25 years, SD = 6; M mass = 75 kg SD = 7; M VO2 peak = 64.8 ml(.)kg(1.)min(-1), SD = 5.2) performed two Tmax tests 1 week apart.1. Values expressed for each participant are means and standard deviations of these two tests. Participants achieved a mean VO2 peak during the Tmax test after 176 s (SD = 40; = 74% of Tmax, SD = 12) and maintained it for 66 s (SD = 39; M = 26% of Tmax, SD = 12). Additionally they obtained mean 95 % of VO2 peak after 147 s (SD = 31; M = 62 % of Tmax, SD = 8) and maintained it for 95 s (SD = 38; M = 38 % of Tmax, SD = 8). These results suggest that 60-70% of Tmax is an appropriate exercise duration for a population of well trained cyclists to attain VO2 peak during exercise at Pmax. However due to intraparticipant variability in the temporal aspects of the VO2 response to exercise at Pmax, future research is needed to examine whether individual high-intensity interval training programs for well trained endurance athletes might best be prescribed according to an athlete's individual VO2 response to exercise at Pmax.

Muscle metabolism during sprint exercise in man: Influence of sprint training

In order to examine the influence of sprint training on metabolism and exercise performance during sprint exercise, 16 recreationally-active, untrained, men (TO2peak= 3.8+/-0.1 1.min(-1)) were randomly assigned to either a training (n=8) or control group (n=8). Each subject performed a 30-sec cycle sprint and a test to measure VO2peak before and after eight weeks of sprint training. The training group completed a series of sprints three times per week which progressed from three 30-sec cycle sprints in weeks 1 and 2, to six 30-sec sprints in weeks 7 and 8. Three mins of passive recovery separated each sprint throughout the training period. Muscle samples were obtained at rest and immediately following the pre- and post-training sprints and analysed for high energy phosphagens, glycogen and lactate; the activities of both phosphofructokinase (PFK) and citrate synthase (CS) were also measured and muscle fibre types were quantified, Training resulted in a 7.1% increase in mean power output (p

Retention, adherence and compliance: Important considerations for home- and group-based resistance training programs for older adults

Reports on the efficacy of physical activity intervention trials usually only include discussion of the primary outcomes. However, assessing factors such as participant retention, adherence and compliance can assist in the accurate interpretation of the overall impact of a program in terms of reach and appeal. A quasi-randomised trial was carried out to assess and compare retention and adherence rates, and compliance with, a twice weekly resistance training program provided either individually at home or in a group format. Retirement villages (n=6) were assigned to either 'Have A Try' (HAT, home-based) or 'Come Have A Try' (CHAT, group-based); both programs included nine strength and two balance exercises. The program involved a 20-week Intervention Phase a 24-week Maintenance Phase and a 20-week On-going Maintenance Phase. One hundred and nineteen participants (mean age 80 +/- 6 years) were recruited (HAT = 38, CHAT = 81). There was no difference in retention rates at the end of the Intervention Phase, but significantly more HAT than CHAT participants had dropped out of the study (p < 0.01) after the Maintenance Phase and the On-going Maintenance Phase. During the Intervention Phase, over half the HAT and CHAT participants completed >= 75% of the prescribed activity sessions, but adherence was significantly greater in CHAT than HAT during the Maintenance Phase (p < 0.01). Participants in CHAT were significantly more compliant than HAT participants (p < 0.05). Both home- and group-based formats were successful over the short-term, but, in retirement villages, the group program had better adherence and compliance in the longer-term. (c) 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Dynamic training volume: A construct of both time under tension and volume load

The purpose of this study was to investigate the effects of three different weight training protocols, that varied in the way training volume was measured, on acute muscular fatigue. Ten resistance-trained males performed all three protocols which involved dynamic constant resistance exercise of the elbow flexors. Protocol A provided a standard for the time the muscle group was under tension (TUT) and volume load (VL), expressed as the product of the total number of repetitions and the load that was lifted. Protocol B involved 40% of the TUT but the same VL compared to protocol A; protocol C was equated with protocol A for TUT but only involved 50% of the VL. Fatigue was assessed by changes in maximum voluntary isometric force and integrated electromyography (iEMG) between the pre- and post-training protocols. The results of the study showed that, when equated for VL, greater TUT produced greater overall muscular fatigue ( p

High- and low-volume resistance training similarly enhances functional performance in older adults

It is well known that resistance training improves muscle strength in older adults and may enhance or preserve functional performance. However, it is unclear if the volume of work undertaken in the elderly alters the response in functional performance. PURPOSE: To investigate the effect of a high- versus low-volume resistance training program on functional performance in older adults. METHODS: Thirty-two healthy men and women aged 65-78 years were randomly assigned to either a single-set (SS, n = 16) or 3-set (MS, n = 16) progressive resistance training program for 20 weeks. Groups trained 2 days per week using machine weights at 8 repetitions maximum (8-RM) for 7 upper and lower body exercises. Muscle strength was assessed by the 1-RM and functional performance by a battery of tests (repeated chair rise, usual and fast 6-m walk, 6-m backwards walk, floor rise to standing, stair climb, and 400-m walk time). RESULTS: Twenty-eight subjects completed the study. There was no difference between groups at baseline in muscle strength or functional performance. Whole body muscle strength significantly increased in both groups with greater gains in the 3-set group (MS 32.9 ± 3.1%; SS 18.6 ± 2.7%, mean ± SE; P < 0.01). Significant improvement (time effect, P < 0.01) occurred for both groups in the chair rise (MS 13.6 ± 3.2%; SS 10.2 ± 3.0%), 6-m backwards walk (MS 14.9 ± 3.3%; SS 14.3 ± 4.2%), stair climb (MS 6.4 ± 2.8%; SS 7.7 ± 3.1%) and 400-m walk (MS 7.4 ± 1.4%; SS 3.9 ± 1.2%). There were no interaction (group × time) effects for functional performance and no differences by sex. CONCLUSION: Resistance training that utilizes either a singleset or 3-set regimen may significantly and similarly improve functional performance in community-dwelling older adults. Enhancement of functional performance may prolong independence and improve quality of life. ©2004The American College of Sports Medicine