Barefoot running improves economy at high intensities and peak treadmill velocity

Aim: Barefoot running can improve running economy (RE) compared to shod running at low exercise intensities, but data is lacking for the higher intensities typical during many distance running competitions. The influence of barefoot running on the velocity at maximal oxygen uptake (vVO2max) and peak incremental treadmill test velocity (vmax) is unknown. The present study tested the hypotheses that barefoot running would improve RE, vVO2max and vmax relative to shod running. Methods: Using a balanced within-subject repeated measures design, eight male runners (aged 23.1±4.5 years, height 1.80±0.06 m, mass 73.8±11.5 kg, VO2max 4.08±0.39 L·min-1) completed a familiarization followed by one barefoot and one shod treadmill running trial, 2-14 days apart. Trial sessions consisted of a 5 minute warm-up, 5 minute rest, followed by 4×4 minute stages, at speeds corresponding to ~67, 75, 84 and 91% shod VO2max respectively, separated by a 1 minute rest. After the 4th stage treadmill speed was incremented by 0.1 km·h-1 every 15 s until participants reached volitional exhaustion. Results: RE was improved by 4.4±7.0% across intensities in the barefoot condition (P=0.040). The improvement in RE was related to removed shoe mass (r2=0.80, P=0.003) with an intercept at 0% improvement for RE at 0.520 kg total shoe mass. Both vVO2max (by 4.5±5.0%, P=0.048) and vmax (by 3.9±4.0%, P=0.030) also improved but VO2max was unchanged (p=0.747). Conclusion: Barefoot running improves RE at high exercise intensities and increases vVO2max and vmax, but further research is required to clarify the influence of very light shoe weights on RE

Relieving thermal discomfort:effects of sprayed L-Menthol on perception, performance and time trial cycling in the heat

L-menthol stimulates cutaneous thermoreceptors and induces cool sensations improving thermal comfort, but has been linked to heat storage responses; this could increase risk of heat illness during self-paced exercise in the heat. Therefore, L-menthol application could lead to a discrepancy between behavioral and autonomic thermoregulatory drivers. Eight male participants volunteered. They were familiarized and then completed two trials in hot conditions (33.5 °C, 33% relative humidity) where their t-shirt was sprayed with CONTROL-SPRAY or MENTHOL-SPRAY after 10 km (i.e., when they were hot and uncomfortable) of a 16.1-km cycling time trial (TT). Thermal perception [thermal sensation (TS) and comfort (TC)], thermal responses [rectal temperature (Trec), skin temperature (Tskin)], perceived exertion (RPE), heart rate, pacing (power output), and TT completion time were measured. MENTHOL-SPRAY made participants feel cooler and more comfortable and resulted in lower RPE (i.e., less exertion) yet performance was unchanged [TT completion: CONTROL-SPRAY 32.4 (2.9) and MENTHOL-SPRAY 32.7 (3.0) min]. Trec rate of increase was 1.40 (0.60) and 1.45 (0.40) °C/h after CONTROL-SPRAY and MENTHOL-SPRAY application, which were not different. Spraying L-menthol toward the end of self-paced exercise in the heat improved perception, but did not alter performance and did not increase heat illness risk

Do Water Safety Lessons Improve Water Safety Knowledge?

A person, usually a child or young adult, dies by drowning every 90 seconds around the planet. Most drowning prevention initiatives do not assess the efficacy of the intervention. In this study, thirteen- to fourteen-year-olds had their level of water safety knowledge (covering cold shock, rips and tides) assessed before, just after, and 3-6 months after one, 25-minute water safety lesson on these topics. We evaluated the knowledge gained and retained on water safety “awareness” (i.e., knowledge of risks) and “confidence” in terms of knowing what to do in an emergency. The results demonstrated that the lesson significantly increased water safety awareness and confidence in pupils, and these benefits were retained for at least six months. We accept our hypothesis that theoretical, classroom-based instruction in water safety can improve the water safety awareness and confidence of children and may represent a “lesson for life.” Given the large numbers who drown around the globe annually, a lesson on water safety should be part of every national curriculum

Prolonged anxiety on habituation of the cold shock response

Variation in the cold shock response (CSR) can be explained by physiological factors, habituation; and possibly "psychological" influences. Acute anxiety on cold-water immersion (CWI) increases the magnitude of the CSR in unhabituated volunteers and eliminates the reduction in the response seen after habituation. Recently it was demonstrated that habituation of the CSR includes a significant perceptual component. When the threat of CWI scenario was reduced, anxiety associated with being immersed was also reduced. In contrast, prolonged anxiety during repeat CWIs may prevent habituation. Therefore, it was hypothesized that prolonged anxiety reduces the extent of CSR habituation