Blood Flow Restricted Training and Time Trial Performance: A Cohort Study of World Class Rowers.

INTRODUCTION: This study aimed to explore the potential impact of incorporating blood-flow restriction (BFR) training within a training block characterized by minimal high-intensity work on 2000-m rowing ergometer time-trial (TT) performance in elite/world-class rowers. Physiological markers often associated with endurance performance (maximal aerobic capacity - VO2max, blood lactate thresholds and hemoglobin mass - Hbmass) were measured to determine whether changes are related to an improvement in performance. METHODS: Using a quasi-experimental, observational study design (no control group), 2000-m TT performance, VO2max, submaximal work rates eliciting blood lactate concentrations of ~2 and ~ 4 mmol·L-1, and Hbmass were measured before and after 4 weeks of non-competitive season training, which included BFR rowing. BFR training consisted of 11 sessions of 2x10 minutes of BFR rowing at a workload equating to blood lactate concentrations of ~2 mmol·L-1. Paired t-tests were used to compare pre/post values, and Pearson correlation was used to examine whether physiological changes were associated with changes to TT performance. RESULTS: TT performance improved in both female (1.09 ± 1.2%, ~4.6 ± 5.2 s; p < 0.01) and male (1.17 ± 0.48%, ~4.5 ± 1.9 s; p < 0.001) athletes. VO2max increased in female rowers only (p < 0.01), but both sexes had an increase in work rates eliciting blood lactate concentrations of 2 (female:184 ± 16 to 195 ± 15 W, p < 0.01; male:288 ± 23 to 317 ± 26 W, p = 0.04) and 4 mmol·L-1 (female:217 ± 13 to 227 ± 14 W, p = 0.02; male:339 ± 43 to 364 ± 39 W, p < 0.01). No changes in Hbmass (both sexes, p = 0.8) were observed. Improvements in TT performance were not related to physiological changes (all correlations p ≥ 0.2). CONCLUSIONS: After 4 weeks of training with BFR, the improvement in TT performance was greater than what is typical for this population. Physiological variables improved during this training block but did not explain improved TT performance.

The Efficacy of Heat Acclimatization Pre-World Cup in Female Soccer Players.

The efficacy of a 14-day field-based heat acclimatization (HA) training camp in 16 international female soccer players was investigated over three phases: phase 1: 8 days moderate HA (22. 1°C); phase 2: 6 days high HA (34.5°C); and phase 3: 11 days of post-HA (18.2°C), with heart rate (HR), training load, core temp (T c), and perceptual ratings recorded throughout. The changes from baseline (day-16) in (i) plasma volume (PV), (ii) HR during a submaximal running test (HRex) and HR recovery (HRR), and (iii) pre-to-post phase 2 (days 8-13) in a 4v4 small-sided soccer game (4V4SSG) performance were assessed. Due to high variability, PV non-significantly increased by 7.4% ± 3.6% [standardized effect (SE) = 0.63; p = 0.130] from the start of phase 1 to the end of phase 2. Resting T c dropped significantly [p < 0.001 by -0.47 ± 0.29°C (SE = -2.45)], from day 1 to day 14. Submaximal running HRR increased over phase 2 (HRR; SE = 0.53) after having decreased significantly from baseline (p = 0.03). While not significant (p > 0.05), the greatest HR improvements from baseline were delayed, occurring 11 days into phase 3 (HRex, SE = -0.42; HRR, SE = 0.37). The 4v4SSG revealed a moderate reduction in HRex (SE = -0.32; p = 0.007) and a large increase in HRR (SE = 1.27; p < 0.001) from pre-to-post phase 2. Field-based HA can induce physiological changes beneficial to soccer performance in temperate and hot conditions in elite females, and the submaximal running test appears to show HRex responses induced by HA up to 2 weeks following heat exposure.

Cardiovascular responses to heat acclimatisation in athletes with spinal cord injury.

OBJECTIVES: To determine the effect of heat acclimatisation (HA) training on blood profile and resting cardiac function in elite athletes with spinal cord injury (SCI). DESIGN: Quasi-experimental. METHODS: Eleven athletes (10m, 1f) with SCI (C5-T3) completed a five-day isothermic HA protocol whereby gastrointestinal temperature (Tc) was elevated to and maintained at ∼38.5 degrees Celsius (°C) via intermittent exercise for sixty minutes each day. Blood samples were collected pre- and post-HA to determine changes in plasma volume (PV). Doppler ultrasound of the left-ventricular outflow tract and 2-d speckle tracking echocardiography were performed in a subset of athletes (n=5) to determine changes in indices of resting left-ventricular function and mechanics, respectively. RESULTS: Ten athletes were successfully able to raise and maintain Tc to 38.5°C. There was a non-significant increase in PV with HA training (ΔPV%: 3.0±5.4%, p=0.086). Following HA, resting HR decreased (63±4 pre-HA vs. 58±5 bpm post-HA, p=0.020), velocity time integral (21.4±2.7 vs. 23.7±3.0cm, p=0.045) and stroke volume increased (64.8±7.6 vs. 70.2±10.5mL, p=0.055). CONCLUSIONS: Our findings suggest a short-term HA protocol in athletes with SCI is safe and may induce beneficial changes in indices of resting left-ventricular function - however results are highly individualized. Future studies on HA in athletes with SCI should focus on determining mechanisms of adaptation and performance outcomes.

Effects of hydration status during heat acclimation on plasma volume and performance.

The impact of hydration status was investigated during a 5-day heat acclimation (HA) training protocol vs mild/cool control conditions on plasma volume (PV) and performance (20 km time-trial [TT]). Sub-elite athletes were allocated to one of two heat training groups (90 min/day): (a) dehydrated to ~2% body weight (BW) loss in heat (35°C; DEH; n = 14); (b) euhydrated heat (35°C; EUH; n = 10), where training was isothermally clamped to 38.5°C core temperature (Tc ). A euhydrated mild control group (22°C; CON; n = 9) was later added, with training clamped to the same relative heart rate (~75% HRmax ) as elicited during DEH and EUH; thus all groups experienced the same internal training stress (%HRmax ). Five-day total thermal load was 30% greater (P < 0.001) in DEH and EUH vs CON. There were significant differences in the average percentage of maximal work rate (%Wmax ) across all groups (DEH: 24 ± 6%; EUH: 34 ± 9%; CON: 48 ± 8%Wmax ) during training required to elicit the same %HRmax (77 ± 4% HRmax ). There were no significant differences pre-to post-HA between groups for PV (DEH: +1.7 ± 10.1%; EUH: +4.8 ± 10.2%; CON: +5.2 ± 4.0%), but there was a significant pooled group PV increase, as well as a 97% likely pooled improvement in TT performance (DEH: -1.8 ± 2.8%; EUH: -1.9 ± 2.1%, CON; -1.8 ± 2.8%; P = 0.136). Due to a lack of between-group differences for PV and TT, but pooled group increases in PV and 97% likely group increase in TT performance, over 5 days of intense training at the same average relative cardiac load suggests that overall training stress may also impact significant adaptations beyond heat and hydration stress.

Analysis of jump performance of world-class mogul skiers over an Olympic quadrennial cycle: a case study.

This case study examines the longitudinal jump data of 1 male and 1 female world-class mogul skier over the course of a quadrennial leading to the 2010 Winter Olympics. Between-subjects standard deviation, smallest worthwhile enhancement, % coefficient of variance, and effect size (ES) were calculated from team jump testing taking place immediately preceding the 2010 Winter Olympics, as this was deemed the point in the quadrennial that the athlete group would be most likely near their best performance. These data were then used to characterize the progression of explosive power of elite mogul skiers over an Olympic quadrennial. Jump data for both the male and the female athlete showed trivial to large improvements in jump performance from Q1 (quadrennial year 1) to Q2, variable changes in performance from Q2 to Q4, and an overall improvement (small to large ES) from Q1 to Q4. Explosive power is a critical component of performance for moguls, and an analysis of the group data (Canadian athletes 2006-2010) shows that of all performance markers, jump testing is the variable that clearly delineates between World Cup and developmental athletes.