The Valsalva maneuver (VM) produces large and abrupt changes in mean arterial pressure (MAP) that challenge cerebral blood flow and oxygenation. We examined the effect of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation responses during (phase I, II, III) and following (phase IV) a VM. Healthy participants (n=20 mean ± SD: 27±7 y) completed 30 and 90% of their maximal VM mouth pressure for 10 s (order randomised) whilst standing. Beat-to-beat MCAv, cerebral oxygenation (NIRS) and MAP across the different phases of the VM are reported as the difference from standing baseline. There were significant interaction (phase * intensity) effects for MCAv, total oxygenation index (TOI) and MAP (all P<0.01). MCAv decreased during phases II and III (P<0.01), with the greatest decrease during phase III (-5 ± 8 and -19 ± 15 cm•s-1 for 30 and 90% VM, respectively). This pattern was also evident in TOI (phase III: -1±1 and -5±4%, both P<0.05). Phase IV increased MCAv (22±15 and 34±23 cm•s-1), MAP (15±14 and 24±17 mm Hg) and TOI (5±6 and 7±5 %) relative to baseline (all P<0.05). Cerebral autoregulation, indexed, as the %MCAv/%MAP ratio, showed a phase effect only (P <0.001), with the least regulation during phase IV (2.4±3.0 and 3.2±2.9). These data illustrate that an intense VM profoundly affects cerebral hemodynamics, with a reactive hyperemia occurring during phase IV following modest ischemia during phases II and III.

The aim of the present study was to analyse the parameters that characterize the vertical ground reaction force during the landing phase of a jump, and to determine the relationship among these parameters in elite soccer players with cerebral palsy (CP). Thirteen male members of the Spanish national soccer team for people with CP (mean age: 27.1 ± 4.7 years) volunteered for the study. Each participant performed three counter movement jumps. The characteristics of the first peak of the vertical ground reaction force during the landing phase of a jump, which corresponds to the forefoot contact with the ground, were similar to the results obtained in previous studies. However, a higher magnitude of rearfoot contact with the ground (F2) was observed in participants with CP than in participants without CP. Furthermore, a significant correlation between F2 magnitude and the elapsed time until its production (T2) was not observed (r = -0.474 for p = 0.102). This result implies that a landing technique based on a delay in the production of F2 might not be effective to reduce its magnitude, contrary to what has been observed in participants without CP. The absence of a significant correlation between these two parameters in the present study, and the high magnitude of F2, suggest that elite soccer players with CP should use footwear with proper cushioning characteristics.

Purpose:The aim of this study was to investigate changes in physiological and performance variables in triathletes following a four week period of reduced training volume and increased training intensity.Methods:Sixteen moderately trained triathletes were randomly allocated to two groups: a control (CON) group which followed their usual training, or a high intensity training (HIIT) group which completed two HIIT sessions per week during four weeks of reduced training volumeResults:Maximal oxygen comsumption (VO2max) increased significantly in the HIIT group (p = .03, d = .5) but remained unchanged in the CON. Cycling power at first and second ventilatory threshold (PVT1 and PVT2) increased significantly in the HIIT subjects (p = .03, d = 1.0) and was unchanged in the CON participants (p = .57). During the simulated triathlon test, pre-post test cycling times and average power (Pav) were unchanged in both groups (p > .05). No significant interactive effects between groups were observed for running time (p ...

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The second ventilatory threshold (VT₂) is established as an important indicator of exercise intensity tolerance. A higher VT₂ allows for greater duration of higher intensity exercise participation and subsequently greater reductions in cardiovascular disease (CVD) risk. This study aimed to compare the efficacy of standardised and individualised exercise prescription on VT₂ among physically inactive adults. Forty-nine physically inactive male and female participants (48.6 ± 11.5 years) were recruited and randomised into a 12-week standardised (n = 25) or individualised (n = 24) exercise prescription intervention. The exercise intensity for the standardised and individualised groups was prescribed as a percentage of heart rate reserve (HRR) or relative to the first ventilatory threshold (VT₁) and VT₂, respectively. Participants were required to complete a maximal graded exercise test at pre-and post-intervention to determine VT₁ and VT₂. Participants were categorised as responders to the intervention if an absolute VT₂ change of at least 1.9% was attained. Thirty-eight participants were included in the analysis. A significant difference in VT₂ change was found between individualised (pre vs. post: 70.6% vs. 78.7% maximum oxygen uptake (VO₂max)) and standardised (pre vs. post: 72.5% vs. 72.3% VO₂max) exercise groups. Individualised exercise prescription was significantly more efficacious (p = 0.04) in eliciting a positive response in VT₂ (15/19, 79%) when compared to the standardised exercise group (9/19, 47%). Individualised exercise prescription appears to be more efficacious than standardised exercise prescription in eliciting a positive VT₂ change among physically inactive adults. Increasing VT₂ allows for greater tolerance to higher exercise intensities and therefore greater cardiovascular health outcomes.