. 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 (PI max ) 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% PI max . Results: The inspiratory muscle strength of the training group increased by 44 Ϯ 25 cm H 2 O (45.3 Ϯ 29.7%) compared with only 6 Ϯ 11 cm H 2 O (5.3 Ϯ 9.8%) of the placebo group (P Ͻ 0.05 within and between groups). The distance covered in the 6-min all-out effort increased by 3.5 Ϯ 1.2% in the training group compared with 1.6 Ϯ 1.0% in the placebo group (P Ͻ 0.05). The time in the 5000-m trial decreased by 36 Ϯ 9 s (3.1 Ϯ 0.8%) in the training group compared with only 11 Ϯ 8 s (0.9 Ϯ 0.6%) in the placebo group (P Ͻ 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 Ϯ 4.3% deficit in PI max to only 3.0 Ϯ 1.6% (P Ͻ 0.05) pre-and post-intervention, respectively. Conclusions: IMT improves rowing performance on the 6-min all-out effort and the 5000-m trial.

The aim of this study was to investigate the effects of sodium bicarbonate (NaHCO) on 4 km cycling time trial (TT) performance when individualised to a predetermined time to peak blood bicarbonate (HCO). Eleven male trained cyclists volunteered for this study (height 1.82 ± 0.80 m, body mass (BM) 86.4 ± 12.9 kg, age 32 ± 9 years, peak power output (PPO) 382 ± 22 W). Two trials were initially conducted to identify time to peak HCO following both 0.2 gkg BM (SBC2) and 0.3 gkg BM (SBC3) NaHCO. Thereafter, on three separate occasions using a randomised, double-blind, crossover design, participants completed a 4 km TT following ingestion of either SBC2, SBC3, or a taste-matched placebo (PLA) containing 0.07 gkg BM sodium chloride (NaCl) at the predetermined individual time to peak HCO. Both SBC2 (-8.3 ± 3.5 s; p < 0.001, d = 0.64) and SBC3 (-8.6 ± 5.4 s; p = 0.003, d = 0.66) reduced the time to complete the 4 km TT, with no difference between SBC conditions (mean difference = 0.2 ± 0.2 s; p = 0.87, d = 0.02). These findings suggest trained cyclists may benefit from individualising NaHCO ingestion to time to peak HCO to enhance 4 km TT performance.

The results of this study demonstrate that in subelite cyclists the relationship between maximum power output and the power output at the lactate threshold, obtained during an incremental exercise test, may change depending on the length of the TT that is completed.

While in vitro work has revealed that dehydration and hyperthermia can elicit increased cellular and oxidative stress, in vivo research linking dehydration, hyperthermia, and oxidative stress is limited. The purpose of this study was to investigate the effects of exercise-induced dehydration with and without hyperthermia on oxidative stress. Seven healthy male, trained cyclists (power output (W) at lactate threshold (LT): 199 ± 19 W) completed 90 min of cycling exercise at 95% LT followed by a 5-km time trial (TT) in 4 trials: (i) euhydration in a warm environment (EU-W, control), (ii) dehydration in a warm environment (DE-W), (iii) euhydration in a thermoneutral environment (EU-T), and (iv) dehydration in a thermoneutral environment (DE-T) (W: 33.9 ± 0.9 °C; T: 23.0 ± 1.0 °C). Oxidized glutathione (GSSG) increased significantly postexercise in dehydration trials only (DE-W: p < 0.01, DE-T: p = 0.03), and while not significant, total glutathione (TGSH) and thiobarbituric acid reactive substances (TBARS) tended to increase postexercise in dehydration trials (p = 0.08 for both). Monocyte heat shock protein 72 (HSP72) concentration was increased (p = 0.01) while lymphocyte HSP32 concentration was decreased for all trials (p = 0.02). Exercise-induced dehydration led to an increase in GSSG concentration while maintenance of euhydration attenuated these increases regardless of environmental condition. Additionally, we found evidence of increased cellular stress (measured via HSP) during all trials independent of hydration status and environment. Finally, both 90-min and 5-km TT performances were reduced during only the DE-W trial, likely a result of combined cellular stress, hyperthermia, and dehydration. These findings highlight the importance of fluid consumption during exercise to attenuate thermal and oxidative stress during prolonged exercise in the heat.

No abstract

The purpose of this study was to examine the effects of a field-based injury prevention exercise on eccentric hamstring strength during simulated soccer match play. Sixteen semiprofessional soccer players (age 21.3 +/- 2.9 years; height 185.0 +/- 8.7 cm; body mass 81.6 +/- 6.7 kg) completed the Soccer-specific Aerobic Field Test (SAFT90), a multidirectional 90-minute exercise protocol representative of soccer match play. Subjects performed 3 maximal dominant-limb isokinetic contractions at 120 degrees x s(-1) for concentric knee extensors (conQ) and flexors (conH), and eccentric knee flexors (eccH) before SAFT90 (t0), at half-time (t45), and immediately after the SAFT90 (t105). After baseline testing, subjects were divided into 2 groups, either performing Nordic hamstring eccentric strengthening exercises during the cool-down (CD) or warm-up (WU) of twice-weekly training sessions. After an 8-week intervention program, the baseline testing was repeated. The WU group displayed a significant increase postintervention in eccH gravity-corrected peak torque (PT) and the functional eccH:conQ ratio at t0 (p < 0.01), a significantly greater improvement compared with CD group (p < 0.05). Conversely, the CD group displayed a significant increase in both eccH PT and the functional eccH:conQ ratio postintervention at t45 (p < 0.05) and at t105 (p < 0.05), which were significantly greater increases compared with the WU group (p < 0.05). These findings indicate that the training intervention had a time-dependent beneficial effect on eccentric hamstring strength and that strength training conducted posttraining significantly reduced the negative influence of fatigue.

No abstract

Despite notably enhanced blood-buffering capacity, NaHCO3 ingestion had no effect on the W', the CP, or the overall performance during 3 min of all-out cycling. It is concluded that preexercise blood alkalosis had no influence on the power-duration relationship for all-out exercise.