Influence of endogenous and exogenous hormones on the cardiovascular response to lower extremity exercise and group III/IV activation in young females.

Oral contraceptive (OC) use can increase resting blood pressure (BP) in females as well as contribute to greater activation of group III/IV afferents during upper body exercise. It is unknown, however, whether an exaggerated BP response occurs during lower limb exercise in OC users. We sought to elucidate the group III/IV afferent activity-mediated BP and heart rate responses, while performing lower extremity tasks during early and late follicular phases in young, healthy females. Females not taking OCs (NOC: n=8; age: 25±4 years) and taking OCs (OC: n=10; age: 23±2 years) completed a continuous knee extension/flexion passive stretch (mechanoreflex) and cycling exercise with sub-systolic cuff occlusion (exercise pressor reflex), which was followed by a two-minute post-exercise circulatory occlusion (PECO) (metaboreflex). Data collection occurred on two occasions: once during the early follicular phase (days 1-4) and once during the late follicular phase (days 10-14) of their menstrual cycle (NOC), or during the placebo and active pill phases (OC). Resting mean arterial BP and heart rate were not different between phases in NOC and OC participants (p>0.05). Hemodynamic responses to metaboreflex, mechanoreflex, and collective exercise pressor reflex activation were not different between phases in both groups (p>0.05). In conclusion, although OCs are known to increase BP at rest, our findings indicate that neither endogenous nor exogenous (OC) sex hormones modulate BP during large, lower-limb muscle exercise, with or without group III/IV afferent activation in young, healthy females.

Effects of marathon training on maximal aerobic capacity and running economy in experienced marathon runners.

Maximal aerobic capacity (VO2max) and running economy (RE) are markers of running performance. A valid evaluation of RE may occur through allometric scaling of body mass (alloVO2; ml kg-0.66 min-1), energy cost (EC; kcal kg-1 km-1), or percent of VO2max (%VO2max). Little is known about physiological changes that occur in competitive runners over a marathon training cycle. The VDOT score, incorporating VO2max and RE, enables comparison of race performances under different temperature conditions. This study's purpose was to determine whether VO2max and measures of RE change with marathon training, and to evaluate the relationship between these variables and VDOT. Eight runners (age 34±2 years; marathon <3:00 males, <3:30 females; five females) completed treadmill marathon-intensity-effort (MIE) and VO2max tests at 10 and 1-2 weeks pre-marathon. Body composition (%BF) was determined using hydrostatic weighing. Paired t-tests were used to compare pre- and post-training values. The alpha level for significance was set at 0.05. Body fat decreased from 18.7±1.5% to 16.7±1.6%, VO2max increased from 51.6±2.4 to 63.9±1.1 ml kg-1 min-1, and %VO2max during the MIE decreased from 82.1±2.0 to 72.3±3.2% (p < 0.05 for all). VDOT was significantly associated with alloVO2 (r = -0.779, p = 0.039) but not with VO2max (r = 0.071, p = 0.867). Experienced competitive runners may increase VO2max and decrease %BF after a marathon-specific training cycle. The decrease in %VO2max in a MIE is likely due to a higher VO2max, as other measures of RE did not change significantly. In this cohort, alloVO2 was negatively correlated with race performance.

Foam rolling is an effective recovery tool in trained distance runners.

Purpose: Many endurance athletes use foam rolling (FR) to decrease muscle soreness, but it is unclear whether FR effectively treats soreness in this population. Moreover, the effects of FR in highly trained runners are unknown. The aim of this study was to use downhill running (DHR) to induce muscle soreness in runners and to determine the influence of FR on soreness and running performance when compared to sham compression tights. Methods: Participants performed a running economy (RE) test at 75% of 5-km race speed and a 3-km time trial (TT). In a crossover design, subjects then completed DHR followed by either a FR protocol or wearing sham compression tights. Two days post-DHR, subjects repeated the RE and TT tests. Crossover visits occurred 2-4 weeks later. During RE tests, VO2 and rating of perceived exertion (RPE) were recorded. Passive and active soreness were measured on a scale of 0 (no soreness) to 10 (extreme soreness). Results: Eight runners (aged 31 ± 7 years; four females; VO2peak 57 ± 7 ml kg-1 min-1) completed the study. Both treatment conditions experienced passive (p = 0.026) and active soreness (p = 0.012) induced by DHR. Active soreness 2 days postDHR was significantly lower after FR than after sham compression tights (p = 0.025). With tights, there was a trend for an increased RPE compared to pre-DHR (p = 0.056). Conclusions: Foam rolling decreases leg soreness in well-trained runners and attenuates soreness-related increases in perceived exertion during sub-maximal running.

The relationships between age and running performance variables in master runners.

Purpose: Peak aerobic capacity (V̇O2peak) declines with age, but running economy (RE) may not. We evaluated VO2peak and RE in master runners and determined whether age is associated with these measures. Methods: In a cross-sectional study, runners completed two running tests within four weeks of a goal race of 10-26.2 miles. Subjects ran for five min at 88% of predicted maximum heart rate, approximating a marathon-intensity effort (MIE), then performed a V̇O2peak test. Running economy in the MIE was measured using oxygen cost with body mass scaled allometrically (alloV̇O2); energy cost (EC), determined using caloric equivalents; and percent of V̇O2peak (%V̇O2peak). Pearson's correlations were used to determine relationships between age and running performance variables. Results: Runners (n = 31, 13 females; mean age 54.9 ± 8.4 years) had a mean VO2peak of 52.5 ± 7.9 ml O2 kg-1 min-1. Age was significantly correlated with V̇O2peak (r = - 0.580, p = 0.001) and alloV̇O2 (r = - 0.454, p = 0.034). Age was related to EC in females (r = 0.649, p = 0.042) and MIE V̇O2 in males (r = - 0.600, p = 0.039). Conclusions: In this population, age was negatively associated with V̇O2peak and alloV̇O2. Females showed a positive relationship between age and EC, while males had a negative correlation between age and MIE V̇O2. Aerobic capacity declines with age, but there may be sex differences in age-related alterations to submaximal running.