Effects Of A Head-Cooling Cap On 5-Km Running Performance In The Heat

International Journal of Exercise Science 16(6): 193-204, 2023. Cooling the head region during exercise can enhance running performance, but this observation is limited to intermittent cooling. This study investigated the effects of continuous head cooling on 5-km running time-trial (TT) performance in hot conditions. Six male and four female triathletes completed two experimental sessions consisting of two 10-minute runs at 50% and 70% O2max followed by a 5-km TT in the heat (32.0±0.3 °C, 50.1±1.2% RH). In a randomized crossover design, either an ice-filled cooling cap or no cooling cap was provided prior to the 10-minute run at 70%O2max. Performance time, rectal, forehead and mean skin temperature, RPE, thermal comfort, fluid loss, blood lactate and heart rate were recorded. Performance time was faster with a cooling cap (1175±80 s) compared to no cooling cap (1189±76 s, P = 0.034; d = 0.18). The cooling cap reduced forehead temperature (P \u3c0.001) and improved thermal comfort (P = 0.004) but had no effect on any other variable (P \u3e 0.05). Continuously cooling the head with an ice-filled cap enhanced 5-km TT performance in the heat. Participants reported an improved thermal comfort with no change in core temperature. Continuously cooling the head may be a practical strategy to enhance running performance in hot conditions

Carbohydrate vs protein supplementation for recovery of neuromuscular function following prolonged load carriage

<p>Abstract</p> <p>Background</p> <p>This study examined the effect of carbohydrate and whey protein supplements on recovery of neuromuscular function after prolonged load carriage.</p> <p>Methods</p> <p>Ten male participants (body mass: 81.5 ± 10.5 kg, age: 28 ± 9 years, <inline-formula><graphic file="1550-2783-7-2-i1.gif"/></inline-formula> O₂max: 55.0 ± 5.5 ml·kg^-1·min^-1) completed three treadmill walking tests (2 hr, 6.5 km·h^-1), carrying a 25 kg backpack consuming 500 ml of either: (1) Placebo (flavoured water) [PLA], (2) 6.4% Carbohydrate Solution [CHO] or (3) 7.0% Whey Protein Solution [PRO]. For three days after load carriage, participants consumed two 500 ml supplement boluses. Muscle performance was measured before and at 0, 24, 48 and 72 h after load carriage, during voluntary and electrically stimulated contractions.</p> <p>Results</p> <p>Isometric knee extension force decreased immediately after load carriage with no difference between conditions. During recovery, isometric force returned to pre-exercise values at 48 h for CHO and PRO but at 72 h for PLA. Voluntary activation decreased immediately after load carriage and returned to pre-exercise values at 24 h in all conditions (<it>P </it>= 0.086). During recovery, there were no differences between conditions for the change in isokinetic peak torque. Following reductions immediately after load carriage, knee extensor and flexor peak torque (60°·s^-1) recovered to pre-exercise values at 72 h. Trunk extensor and flexor peak torque (15°·s^-1) recovered to pre-exercise values at 24 h (<it>P </it>= 0.091) and 48 h (<it>P </it>= 0.177), respectively.</p> <p>Conclusion</p> <p>Recovery of neuromuscular function after prolonged load carriage is improved with either carbohydrate or whey protein supplementation for isometric contractions but not for isokinetic contractions.</p

New Zealand blackcurrant extract enhances muscle oxygenation during repeated intermittent forearm muscle contractions in advanced and elite rock climbers

Anthocyanin-rich New Zealand blackcurrant (NZBC) may improve forearm muscle oxygenation and enhance performance in high-level rock climbers. As such, using a double-blind, randomized, cross-over design study, twelve participants performed an oxidative capacity assessment, and two successive exhaustive exercise trials (submaximal forearm muscle contractions at 60 % of their maximal volitional contraction). Each visit was conducted following 7-days intake of 600 mg·day-1 NZBC extract or placebo. Oxidative capacity was estimated by calculating the oxygen half time recovery using near infrared spectroscopy. Time to exhaustion (s), impulse (kg·s), and minimum tissue saturation index (min-TSI %) were assessed during both the exercise trials. Muscle oxidative capacity was greater with NZBC (mean difference [MD] = 5.3 s, 95% confidence intervals [95% CI] = 0.4 – 10.2 s; p = 0.036; Cohen’s d = 0.94). During the exercise trials, there was an interaction for min-TSI % (time x condition, p = 0.046; ηp2 = 0.372), which indicated a greater level of oxygen extraction during trial two with NZBC extract (MD = 9 %, 95% CI = 2-15 %) compared to the placebo (MD = 2 %, 95% CI = 1 - 7 %). There was a decrease in time to exhaustion (p <0.001, ηp2 =0.693) and impulse (p = 0.001, ηp2 =0.672) in exercise trial two, with no effect of NZBC extract. In high level rock climbers 7-days NZBC extract improves forearm muscle oxygenation with no effect on isolated forearm muscle performance

New Zealand Blackcurrant Extract Improves Cycling Performance and Fat Oxidation in Cyclists

PURPOSE: Blackcurrant intake increases peripheral blood flow in humans, potentially by anthocyanin-induced vasodilation which may affect substrate delivery and exercise performance. We examined the effects of New Zealand blackcurrant (NZBC) extract on substrate oxidation, cycling time-trial performance and plasma lactate responses following the time-trial in trained cyclists. METHODS: Using a randomized, double-blind, crossover design, fourteen healthy men (age: 38 ± 13 years, height: 178 ± 4 cm, body mass: 77 ± 9 kg, V?O2max: 53 ± 6 ml·kg-1·min-1, mean ± SD) ingested NZBC extract (300 mg?day-1 CurraNZ™ containing 105 mg anthocyanin) or placebo (PL, 300 mg microcrystalline cellulose M102) for 7-days (washout 14-days). On day 7, participants performed 30 min of cycling (3x10 min at 45, 55 and 65% V?O2max), followed by a 16.1 km time-trial with lactate sampling during a 20-minute passive recovery. RESULTS: NZBC extract increased fat oxidation at 65% V?O2max by 27% (P < 0.05) and improved 16.1 km time-trial performance by 2.4% (NZBC: 1678 ± 108 s, PL: 1722 ± 131 s, P < 0.05). Plasma lactate was higher with NZBC extract immediately following the time-trial (NZBC: 7.06 ± 1.73 mmol?L-1, PL: 5.92 ± 1.58 mmol?L-1 P < 0.01). CONCLUSIONS: Seven days intake of New Zealand blackcurrant extract improves 16.1 km cycling time-trial performance and increases fat oxidation during moderate intensity cycling

Effect of Substitution Time on Physical, Technical and Cognitive Performance in Sub-Elite Male Field Hockey Players

International Journal of Exercise Science 16(6): 497-512, 2023. We examined the effects of substitution time (i.e., recovery time) in a simulated field hockey test on physical, technical and perceptual/cognitive performance. Nine sub-elite male field hockey players (age: 20 ± 2 yrs, height: 1.81 ± 0.06 m, body mass: 71 ± 10 kg, body fat: 10.3 ± 3.7%, O2max: 67 ± 3 completed four 8-min 40-s bouts of high-intensity intermittent exercise with 2-min and 5.5-min substitution time replicating the demands of a 4-quarter field hockey match. After each bout, a 15-m maximal sprint, agility/dribbling test, passing accuracy test, and a cognitive task were completed. Heart rate (p \u3c .001) and rating of perceived exertion (RPE) (p \u3c .001) increased with every bout. RPE was higher for the 5.5-min condition during the 2nd and 4th bout. No differences were observed between the substitution times and the number of bouts on 15-m maximal sprint time (2-min: 2.03 ± 0.14 s, 5.5-min: 2.07 ± 0.12 s), average reaction time (2-min: 347.19 ± 30.78 ms, 5.5-min: 346.69 ± 38.73 ms), cognitive error rate (2-min: 0.86 ± 0.77; 5.5-min: 0.44 ± 0.37), passing accuracy (2-min: 6 ± 1, 5.5-min: 6 ± 1) and agility/dribbling time (2-min: 7.06 ± 0.41 s, 5.5-min: 7.23 ± 0.55 s). It was concluded that a longer recovery time (i.e., substitution time 5.5-min) did not provide better physical and technical performance than 2-min during a simulated 4-quarter field hockey test. Further research with a larger sample size should address whether the shorter 2-min substitution time seemed to result in lower cognitive performance

Beneficial Effects of New Zealand Blackcurrant Extract on Maximal Sprint Speed during the Loughborough Intermittent Shuttle Test

New Zealand blackcurrant (NZBC) extract has been shown to enhance high-intensity intermittent treadmill running. We examined the effects of NZBC extract during the Loughborough Intermittent Shuttle Test (LIST) which involves 5 × 15 min blocks with intermittent 15-m maximal sprints, interspersed by moderate and high-intensity running to simulate team sport activity, and a subsequent run to exhaustion. Thirteen males (age: 22 ± 1 year, V ˙ O 2 max : 50 ± 5 mL·kg−1·min−1) participated in three indoor sessions (T: 24 ± 3 °C, humidity: 52% ± 9%). In the first session, a multistage fitness test was completed to determine peak running speed and estimate V ˙ O 2 max . Participants consumed NZBC extract in capsules (300 mg·day−1 CurraNZ™) or placebo (PL) (300 mg·day−1 microcrystalline cellulose M102) for seven days in a double-blind, randomized, cross-over design (wash-out at least seven days). NZBC extract did not affect average 15-m sprint times in each block. NZBC reduced slowing of the fastest sprint between block 1 and 5 (PL: 0.12 ± 0.07 s; NZBC: 0.06 ± 0.12 s; p &lt; 0.05). NZBC extract had no effect on heart rate, vertical jump power, lactate and time to exhaustion (PL: 13.44 ± 8.09 min, NZBC: 15.78 ± 9.40 min, p &gt; 0.05). However, eight participants had higher running times to exhaustion when consuming NZBC extract. New Zealand blackcurrant extract may enhance performance in team sports with repeated maximal sprints