Showing papers by "David A. Jones published in 2001"

Inspiratory muscle training improves rowing performance

Abstract: VOLIANITIS, S., A. K. MCCONNELL, Y. KOUTEDAKIS, L. MCNAUGHTON, K. BACKX, and D. A. JONES. Inspiratory muscle training improves rowing performance. Med. Sci. Sports Exerc., Vol. 33, No. 5, 2001, pp. 803‐ 809. Purpose: To investigate the effects of a period of resistive inspiratory muscle training (IMT) upon rowing performance. Methods: Performance was appraised in 14 female competitive rowers at the commencement and after 11 wk of inspiratory muscle training on a rowing ergometer by using a 6-min all-out effort and a 5000-m trial. IMT consisted of 30 inspiratory efforts twice daily. Each effort required the subject to inspire against a resistance equivalent to 50% peak inspiratory mouth pressure (PImax) by using an inspiratory muscle training device. Seven of the rowers, who formed the placebo group, used the same device but performed 60 breaths once daily with an inspiratory resistance equivalent to 15% PImax. Results: The inspiratory muscle strength of the training group increased by 44 6 25 cm H2O (45.3 6 29.7%) compared with only 6 6 11 cm H2O (5.3 6 9.8%) of the placebo group (P , 0.05 within and between groups). The distance covered in the 6-min all-out effort increased by 3.5 6 1.2% in the training group compared with 1.6 6 1.0% in the placebo group (P , 0.05). The time in the 5000-m trial decreased by 36 6 9 s (3.1 6 0.8%) in the training group compared with only 11 6 8 s (0.9 6 0.6%) in the placebo group (P , 0.05). Furthermore, the resistance of the training group to inspiratory muscle fatigue after the 6-min all-out effort was improved from an 11.2 6 4.3% deficit in PImax to only 3.0 6 1.6% (P , 0.05) pre- and post-intervention, respectively. Conclusions: IMT improves rowing performance on the 6-min all-out effort and the 5000-m trial. Key Words: RESPIRATORY MUSCLE TRAINING, PERFORMANCE ENHANCEMENT, INSPIRATORY MOUTH PRESSURE, RESPIRATORY FATIGUE, DYSPNEA

Assessment of maximum inspiratory pressure. Prior submaximal respiratory muscle activity ('warm-up') enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement.

Abstract: Background : The variability of maximal inspiratory pressure (PImax) in response to repeated measurement affects its reliability; published studies have used between three and twenty

Specific respiratory warm-up improves rowing performance and exertional dyspnea

Abstract: VOLIANITIS, S., A. K. MCCONNELL, Y. KOUTEDAKIS, and D. A. JONES. Specific respiratory warm-up improves rowing performance and exertional dyspnea. Med. Sci. Sports Exerc., Vol. 33, No. 7, 2001, pp. 1189 ‐1193. Purpose: The purpose of this study was a) to compare the effect of three different warm-up protocols upon rowing performance and perception of dyspnea, and b) to identify the functional significance of a respiratory warm-up. Methods: A group of well-trained club rowers (N 5 14) performed a 6-min all-out rowing simulation (Concept II). We examined differences in mean power output and dyspnea measures (modified CR-Borg scale) under three different conditions: after a submaximal rowing warm-up (SWU), a specific rowing warm-up (RWU), and a specific rowing warm-up with the addition of a respiratory warm-up (RWUplus) protocol. Results: Mean power output during the 6-min all-out rowing effort increased by 1.2% after the RWUplus compared with that obtained after the RWU (P , 0.05) which, in turn, was by 3.2% higher than the performance after the SWU (P , 0.01). Similarly, after the RWUplus, dyspnea was 0.6 6 0.1 (P , 0.05) units of the Borg scale lower compared with the dyspnea after the RWU and 0.8 6 0.2 (P , 0.05) units lower than the dyspnea after the SWU. Conclusion: These data suggest that a combination of a respiratory warm-up protocol together with a specific rowing warm-up is more effective than a specific rowing warm-up or a submaximal warm-up alone as a preparation for rowing performance.

Is glucose/amino acid supplementation after exercise an aid to strength training?

Abstract: Background—The precise timing of carbohydrate and amino acid ingestion relative to a bout of resistance exercise may modulate the training eVect of the resistance exercise. Objective—To assess whether regular glucose/amino acid supplementation immediately after resistance exercise could enhance the gain in muscle strength brought about by resistance training. Methods—Seven untrained participants with a median age of 23 years and mean (SD) body mass 68.9 (13.5) kg resistance trained on a leg extension machine for five days a week for 10 weeks, using four sets of 10 repetitions. Alternate legs were trained on successive days, one leg each day. Subjects ingested either a supplement including 0.8 g glucose/kg and 0.2 g amino acids/ kg, or placebo, on alternate training days immediately after training. Therefore the supplement was always ingested after training the same leg (supplement leg). Isometric, isokinetic, and 1 repetition maximum (RM) strength were measured before, during, and after training. Blood samples were analysed to determine the acute responses of insulin and glucose to resistance exercise and supplementation or placebo. Results—Serum insulin concentration peaked 20 minutes after supplement ingestion at ninefold the placebo level, and remained significantly elevated for at least 80 minutes (p 0.05). Conclusion—Regular glucose/amino acid supplementation immediately after resistance exercise is unlikely to enhance the gain in muscle strength brought about by resistance training. (Br J Sports Med 2001;35:109‐113)

Acute muscle damage as a stimulus for training-induced gains in strength

Abstract: PURPOSE: The purpose of this study was to investigate the effect of a single acute bout of maximal eccentric work upon the strength gains during 9 subsequent weeks of strength training. Eccentric work causes acute muscle damage that may initiate compensatory hypertrophy and enhance training-induced gains in strength. METHODS: Twenty-six healthy adults (21 +/- 1 yr, 7 women) trained the elbow flexors 3 d per week for 9 wk. One arm (C) performed purely conventional isotonic training, i.e., lifting and lowering. The other arm (E) began with a single bout of maximal eccentric work but thereafter undertook identical isotonic training. Every week dynamic lifting strength (1 RM) and isometric strength were measured. RESULTS: The results indicated that an acute bout of eccentric muscle damage does not accentuate training-induced gains in strength. Isometric strength of arm E fell by 15 +/- 2% (mean +/- SEM) 2 d after the bout of eccentric work, and, 4 d afterward, plasma creatine kinase levels were 1502 +/- 397 IU.L-1. Although arm E displayed rapid gains in strength from 2 d after the bout of eccentric work, these were not sustained, and for several weeks arm E showed significantly smaller gains in strength than arm C (isometric strength, 2 wk; dynamic lifting strength, 5 wk). CONCLUSIONS: After 9 wk of training, the gains in both isometric and dynamic lifting strength were similar for the two arms. A single bout of damaging eccentric work did not enhance the response to conventional strength training and significantly compromised strength gains for several weeks.

Quantifying the 5-HT1A agonist action of buspirone in man.

Abstract: Rationale: Buspirone is used as a neuroendocrine challenge in which the increase of circulating prolactin is taken as a measure of the sensitivity of central serotonergic (5-HT1A) pathways. Interpretation of the test is complicated, however, by the fact that buspirone possesses D2 antagonist and 5-HT1A agonist activity, both of which will result in the release of prolactin. To understand the significance of prolactin secretion in response to buspirone, it is important to measure the differential actions of the two controlling pathways. Objective: To characterise the dual action of buspirone in stimulating the secretion of prolactin by blocking the 5-HT1A action with the 5-HT1A antagonist action of pindolol. Methods: Healthy male subjects (n=35) received buspirone (0.5 mg·kg bw–1 orally) with and without pre-treatment with the 5-HT1A receptor antagonist pindolol (40 mg over 2 days, 0.5 mg·kg bw–1 on test day). Nine subjects underwent two additional trials in which they received a placebo with and without pre-treatment with pindolol. Results: Pindolol alone caused a small but significant reduction (18%) in the tonic release of prolactin. Buspirone alone produced a robust prolactin response which was reduced to approximately half by pindolol pre-treatment. Pindolol pre-treatment also, on average, delayed the onset and peak of the prolactin response. There was wide variation among individuals both in the absolute response to buspirone and in the proportion that could be attributed to the non-serotonergic agonist action of buspirone (22–82% IQ range). Conclusions: Our results indicate that while serotonergic pathways play a minor role in the tonic release of prolactin, the response to a buspirone challenge alone cannot be used as a simple index of central serotonergic activity. However, if two challenges are carried out, one with buspirone and the other with buspirone plus pindolol, quantitative measures can be made of the sensitivity of both the 5-HT1A and the putative D2 pathways controlling prolactin release.