Burns, Stephen Francis

There were three objectives to this proposal: (i) to develop an ecologically valid match­fitness test for badminton players -the badminton intermittent shuttle test (BIST); (ii) to determine the reliability and physiological validity of the test; and (iii) to examine the influence of fatigue, induced by the BIST, on badminton performance.

This study examined the combined effects of breakfast and exercise on short-term academic and cognitive performance in adolescents. Eighty-two adolescents (64 female), aged 14–19 years, were randomized to four groups over a 4-hour morning: (i) a group who fasted and were sedentary (F-S); (ii) a group who ate breakfast but were sedentary (B-S); (iii) a group who fasted but completed a 30-min exercise bout (F-E); and (iv) a group who ate breakfast and completed a 30-min exercise bout (B-E). Individuals completed academic and cognitive tests over the morning. Adolescents in B-E significantly improved their mathematics score (B-E: 15.2% improvement on correct answers, vs. F-S: 6.7% improvement on correct answers; p = 0.014) and computation time for correct answers (B-E: 16.7% improvement, vs. F-S: 7.4% improvement; p = 0.004) over the morning compared with the F-S group. The B-E group had faster reaction times for congruent, incongruent and control trials of the Stroop Color-Word Task compared with F-S mid-morning (all p < 0.05). Morning breakfast and exercise combine to improve short-term mathematical task performance and speed in adolescents.

Purpose This study examined the thermoregulatory response and ergogenic effects of ice slurry (ICE) ingestion in hot environments with high and low relative humidity (RH). Methods Eight males completed four trials in a crossover manner in dry (DRY: 34.7 ± 0.2 °C, 38 ± 2%RH) and humid heat (HUM: 34.8 °C ± 0.2 °C, 80 ± 1%RH). They ingested 8.0 g·kg−1 of ICE (0.0 °C) or 37.5 °C water (CON) during 30 min before exercise, and three aliquots (3.2 g·kg−1) of ICE or CON during 45-min cycling at 50%V˙ O2peak, followed by cycling to exhaustion at 80%V˙ O2peak (TTE). Body core temperature (Tcore), mean skin temperature (Tsk), heart rate (HR), thermal comfort, thermal sensation and rating of perceived exertion (RPE) were measured. Results Relative to CON, ICE improved TTE by 76.5 ± 96.5% in HUM and 21.3 ± 44.9% in DRY (p = 0.044). End-exercise Tcore was lower in ICE versus CON in DRY (37.8 ± 0.4 °C versus 38.1 ± 0.3 °C, p = 0.005) and HUM (38.8 ± 0.4 °C versus 39.3 ± 0.6 °C, p = 0.004). ICE decreased HR, heat storage and heat strain index only in DRY (p < 0.001–0.018). ICE improved thermal sensation and comfort in DRY and HUM (p < 0.001–0.011), attenuated RPE in HUM (p = 0.012) but not in DRY (p = 0.065). Conclusion ICE tended to benefit performance in humid heat more than in dry heat. This is likely due to the reduced extent of hyperthermia in dry heat and the relative importance of sensory inputs in mediating exercise capacity.

It is commonly believed that massage can reduce muscle stiffness and is desirable for recovery from exercise. However, the effect massage on muscle stiffness following eccentric exercises is currently unknown. This study aimed to examine the effect of postexercise massage on passive muscle stiffness over a five-day period. A randomised cross-over study design was adopted. After 40 minutes of downhill running, 18 male recreational runners had one leg received a 16-minute massage and the contralateral leg received a 16-minute sham ultrasound treatment. Passive stiffness for four leg muscles (rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius) was assessed using myotonometry at baseline, immediately post-run, post-treatment, 24, 48, 72, and 96 hours post-run. A 2 (treatment) × 7 (time) mixed ANOVA was conducted with a robust procedure on the myotonometry data of each leg muscle to examine the effect of treatment on stiffness. Passive stiffness for all muscles changed over time but no treatment effect was found. Stiffness increased at 24 hours post-run and remained elevated from baseline levels for up to 96 hours across all four muscles. Significant treatment × time interaction was only found in the tibialis anterior but no post-hoc differences were identified. Passive stiffness of major leg muscles increased after a bout of unaccustomed eccentric exercise and remained elevated for up to four days post-exercise. Compared with the placebo treatment, post-exercise massage had no beneficial effect in alleviating altered muscle stiffness in major leg muscles.

Dietary nitrate supplementation has shown promising ergogenic effects on endurance exercise. However, at present there is no systematic analysis evaluating the effects of acute or chronic nitrate supplementation on performance measures during high-intensity interval training (HIIT) and sprint interval training (SIT). The main aim of this systematic review and meta-analysis was to evaluate the evidence for supplementation of dietary beetroot—a common source of nitrate—to improve peak and mean power output during HIIT and SIT. A systematic literature search was carried out following PRISMA guidelines and the PICOS framework within the following databases: PubMed, ProQuest, ScienceDirect, and SPORTDiscus. Search terms used were: ((nitrate OR nitrite OR beetroot) AND (HIIT or high intensity or sprint interval or SIT) AND (performance)). A total of 17 studies were included and reviewed independently. Seven studies applied an acute supplementation strategy and ten studies applied chronic supplementation. The standardised mean difference for mean power output showed an overall trivial, non-significant effect in favour of placebo (Hedges’ g = −0.05, 95% CI −0.32 to 0.21, Z = 0.39, p = 0.69). The standardised mean difference for peak power output showed a trivial, non-significant effect in favour of the beetroot juice intervention (Hedges’ g = 0.08, 95% CI -0.14 to 0.30, Z = 0.72, p = 0.47). The present meta-analysis showed trivial statistical heterogeneity in power output, but the variation in the exercise protocols, nitrate dosage, type of beetroot products, supplementation strategy, and duration among studies restricted a firm conclusion of the effect of beetroot supplementation on HIIT performance. Our findings suggest that beetroot supplementation offers no significant improvement to peak or mean power output during HIIT or SIT. Future research could further examine the ergogenic potential by optimising the beetroot supplementation strategy in terms of dosage, timing, and type of beetroot product. The potential combined effect of other ingredients in the beetroot products should not be undermined. Finally, a chronic supplementation protocol with a higher beetroot dosage (>12.9 mmol/day for 6 days) is recommended for future HIIT and SIT study.

Far infrared radiation (FIR) within the wavelength range of 4–14 μm can offer human health benefits, such as improving blood flow. Therefore, additives that emit far infrared radiation have the potential to be incorporated into polymer/fabric matrices to develop textiles that could promote health. In this study, biochar derived from candlenuts and pyrolyzed with activated carbon (AC) was incorporated into polypropylene (PP) films and investigated for its potential as a health-promoting textile additive. The properties of biochar were compared with other far infrared (FIR) emitting additives such as hematite, Indian red ochre, and graphene. The addition of biochar increased FIR emissivity to 0.90, which is 9% higher than that of pristine PP. Additionally, biochar enhanced UV and near-infrared (NIR) blocking capabilities, achieving an ultra-protection factor (UPF) of 91.41 and NIR shielding of 95.85%. Incorporating 2 wt% biochar resulted in a 3.3-fold higher temperature increase compared to pristine PP after 30 s of exposure to an FIR source, demonstrating improved heat retention. Furthermore, the ability to achieve the lowest thermal effusivity among other additives supports the potential use of biochar-incorporated fabric as a warming material in cold climates. The tensile properties of PP films with biochar were superior to those with other additives, potentially contributing to a longer product lifespan. Additionally, samples with red ochre exhibited the highest FIR emissivity, while samples with hematite showed the highest capacity for UV shielding.

This study investigated the effect of four days low energy availability (LEA) on physiological markers and mood states in male endurance runners. Twelve participants (mean (standard deviation)); age: 25.8 (3.8) years; fat free mass (FFM): 52.8 (5.5) kg) completed three 4-day conditions: Adequate Energy Availability, AEA: 45 kcal/kgFFM/day; LEA1: 30 kcal/kgFFM/day; and LEA2: 15 kcal/kgFFM/day), in a randomized order. Participants ran on a treadmill at 65% of V̇O2max until they expended 15 kcal/kg FFM/day of energy. Energy intake was adjusted to achieve the desired EA. Pre- and post- measurements of bone turnover, metabolism, testosterone and estradiol (plasma), resting metabolic rate (indirect calorimetry), and mood states (Brunel Mood Scale) were assessed. The results reported a significant decrease in testosterone (condition × time interaction, p=0.03) occurred on LEA2 (Pre: 23.8 (7.0) nmol/L vs Post: 20.3 (7.7) nmol/L) compared with AEA (Pre: 22.9 (5.5) nmol/L vs Post: 23.3 (6.1) nmol/L) or LEA1 (Pre: 23.6 (8.6) nmol/L vs Post: 20.9 (8.8) nmol/L). Fatigue level significantly increased (condition × time interaction, p=0.02) in LEA2 (Pre: 3.5 (1.7) vs Post: 6.5 (2.9)) but did not change in AEA (Pre: 2.8 (1.5) vs Post: 2.5 (2.7)) or LEA1 (Pre: 2.8(2.4) vs Post: 2.9 (2.0)). Other measures were unaffected by the interventions. In conclusion, this study suggests testosterone and fatigue may serve as early indicators of LEA in male runners. However, other physiological markers and mood states appeared largely unaffected, aligning with existing literature indicating minimal disruption of physiological functions during acute LEA in male athletes.

The objective of the current study was to examine the trends of physical activity (PA) and sedentary behaviour (SB) of adolescents in Singapore with two datasets 15 years apart (2006 and 2021). A total sample of 1075 secondary students (mean age = 14.91 ± 0.43 years old) from 15 schools in Singapore took part in the study. A seven-day recall Self-administered Physical Activity Checklist (SAPAC) questionnaire was used to capture time spent on the internet/computer, gaming, homework, reading, sitting and talking/listening to music, telephone, television watching, and PA. Results showed that the 2021 sample spent significantly more time on gaming, homework, sit and talk/listening to music, phone, and PA compared to the 2006 sample, while time spent watching television was significantly lower than the 2006 sample. Both datasets found PA had low or close to zero correlations with all the seven SB, however, the patterns of correlations were different in the two datasets, indicating changes in the trends of SB and PA. Cluster analysis found similar cluster profiles in the two samples but the cluster proportions for certain profiles were different from the two datasets. Significant sex differences were also found in the cluster compositions. Overall, this study shows that PA and SB trends of adolescents have changed significantly.