Journal Articles

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    Effects of acute caffeine intake on muscular power during resistance exercise: a systematic review and meta-analysis
    (Frontiers Media S.A., 2025-10-07) Barnes M
    Background: This study examined the effects of caffeine on movement velocity and power output during resistance exercises and explored moderating factors influencing these effects. Methods: A systematic search of five databases was conducted through June 2025. A random-effects model was used to assess the effect of caffeine on muscular power-related variables, such as bar velocity and power output, during resistance exercises with a fixed number of repetitions. Subgroup analyses were performed based on sex, caffeine dose, habitual caffeine consumption, muscle group, and load. Results: Twelve studies comprising 230 participants were included. Caffeine significantly improved mean velocity (SMD = 0.42, 95% CI: 0.19–0.65, p < 0.05, I2 = 85%) and mean power output (SMD = 0.21, 95% CI: 0.12–0.30, p < 0.05, I2 = 14%) during resistance exercises. Greater improvements in mean velocity were observed in males (SMD: 0.56 vs. 0.22), and habitual caffeine consumption < 3 mg/kg/day (SMD: 0.87 vs. 0.21) (all p < 0.01 for subgroup comparisons). Furthermore, although caffeine increased mean velocity at all caffeine doses (SMD: 0.31–0.78), muscle groups (SMD: 0.32–0.54) and loads (SMD: 0.37–0.49) (all p < 0.01), no significant differences were observed between subgroups (all p > 0.01 for subgroup comparison). Conclusion: Caffeine ingestion enhances movement velocity and power output during resistance exercises, regardless of load. These benefits were more pronounced in males, at higher caffeine doses, among low habitual caffeine consumers, and during lower-body exercises.
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    Effect of Caffeinated Chewing Gum on Maximal Strength, Muscular Power, and Muscle Recruitment During Bench Press and Back Squat Exercises
    (MDPI (Basel, Switzerland), 2025-07-28) Ding L; Liu J; Ma Y; Lei T-H; Barnes M; Guo L; Chen B; Cao Y; Girard O
    Background/Objectives: This study aims to investigate the effects of caffeinated chewing gum on maximal strength, muscular power, and neural drive to the prime movers during bench press and back squat in resistance-trained men. Methods: Sixteen resistance-trained males participated in a double-blind, randomized trial, chewing either caffeinated gum (4 mg/kg) or placebo gum on two separate occasions, seven days apart. After chewing for 5 min, participants performed a maximal strength test followed by muscular power assessments at 25%, 50%, 75%, and 90% of their one-repetition maximum (1RM), completing with 3, 2, 1, and 1 repetition (s), respectively, for bench press and back squat. Surface electromyography data were recorded for each repetition. Results: Caffeinated gum did not significantly improve one-repetition maximum (1RM) for bench press (p > 0.05), but increased mean frequency (MF) and median frequency (MDF) in anterior deltoid, pectoralis major, and biceps brachii (all p < 0.05) compared to placebo. For back squat, 1RM increased with caffeinated gum, along with higher MF and MDF in vastus medialis (all p < 0.05). Caffeinated gum also improved mean and peak velocities, and mean and peak power outputs at 25–75% 1RM during the bench press (all p < 0.05), along with elevated MDF in pectoralis major and biceps brachii (all p < 0.05). Similar improvements were seen in mean and peak velocities during the back squat at 25–90% 1RM (all p < 0.05), along with higher MF and MDF in vastus medialis and increased normalized root mean square activity in gluteus maximus (all p < 0.05). Conclusions: Caffeinated chewing gum (4 mg/kg) enhanced muscular power (25–75% 1RM) in the bench press and improved maximal strength and muscular power (25–90% 1RM) in the back squat by increasing muscle recruitment in resistance-trained men.
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    The dose-dependent effect of acute ozone exposure on lung function and the efficacy of a Boysenberry apple powder blend (BerriQi®) in reducing throat irritation and symptom recovery time in healthy adults
    (Elsevier B V, 2025-09-01) Lomiwes D; Barnes M; Nicholls G; Ngametua N; Sawyer G; Kanon AP; Vangala G; Shaw O
    Urbanization and industrialization have impacted air quality and health, with ozone exposure linked to reduced lung function and increased respiratory issues. This study characterised the dose-dependent effect of acute, controlled ambient ozone exposure in an environmental chamber on lung function, then investigated the effect of BerriQi® Boysenberry and apple powder (BerriQi) ozone-induced respiratory irritation symptoms. In an incremental dose study, healthy adults were exposed to 0.1, 0.2 or 0.3 ppm ozone for 2 h. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were measured at designated timepoints up to 48 h after ozone exposure. This was followed by a randomised, double-blind, placebo-controlled crossover trial, with healthy adults (n = 20) who consumed either BerriQi or a placebo daily for 5 days before being exposed to 0.2 ppm ozone for 2 h. Respiratory irritation symptoms, including throat irritation (TI), soreness of cough (SOC), shortness of breath (SOB), and pain on deep inspiration (PODI), were assessed at designated timepoints up to 48 h after ozone exposure. Our results showed that 0.2 ppm ozone was the maximum tolerated dose that elicited a temporal decline in lung function in healthy participants and that BerriQi supplementation significantly reduced TI (p = 0.04), and may expedite the resolution of SOC, SOB and PODI after acute ozone exposure. These findings suggest that BerriQi may alleviate the severity and duration of ozone-induced respiratory irritation and highlights the potential of BerriQi as a dietary intervention for mitigating the respiratory effects of air pollution.
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    Editorial: Nutrition and muscle recovery after exercise
    (Frontiers Media S.A., 2024-04-23) Cornish SM; Barnes M
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    Emerging transitions in organic waste infrastructure in Aotearoa New Zealand
    (John Wiley and Sons, Inc., 2023-04-01) Diprose G; Dombroski K; Sharp E; Yates A; Peryman B; Barnes M
    Aotearoa New Zealand is at a critical juncture in reducing and managing organic waste. Research has highlighted the significant proportion of organic waste sent to landfills and associated adverse effects such as greenhouse gas emissions and loss of valuable organic matter. There is current debate about what practices and infrastructure to invest in to better manage and use organic waste. We highlight the diversity of existing organic waste practices and infrastructures, focusing on Auckland, Wellington and Christchurch. We show how debates about organic waste practices and infrastructure connect across three themes: waste subjectivities, collective action in place and language.
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    An experimental model of contusion injury in humans
    (Public Library of Science, 17/11/2022) Barnes M; Lomiwes D; Parry DAD; Stephen M
    Introduction Contusion injuries are common in sport, but our knowledge of the responses to injury primarily come from animal studies and research using eccentric exercise. Therefore, the aim of this study was to develop a model of contusion injury in human participants and, additionally, investigate and compare physiological responses to four impact loads. Methods Thirty-two males were exposed to a single impact of either 4.2, 5.2, 6.2 or 7.2kg, dropped from 67 cm, on to the vastus lateralis of one leg. Maximum voluntary and electrically induced quadriceps force, and pressure pain threshold were measured, and blood sampling carried out, prior to and 30min, 24, 48 and 72h post-impact. Magnetic resonance imaging was carried out 24h post-impact to quantify oedema. Results Despite impact force with 7.2kg (1681.4 ± 235.6 N) not being different to 6.2kg (1690.7 ± 117.6 N), 7.2kg resulted in greater volume of oedema, voluntary force loss, pain and elevations in creatine kinase than the other loads. Although electrically induced force changed over time, post-hoc analysis failed to identify any changes. Interleukin-6 and prostaglandin-E2 did not change over time for any of the loads. Significant correlations were found between oedema volume, pressure pain threshold and maximum voluntary contraction force. Conclusions This is the first experimental study to investigate traumatic loading of skeletal muscle and the subsequent physiological responses associated with contusion injuries in humans. The absence of immediate elevations in creatine kinase and changes in electrically induced force suggest impact, with forces similar to those experienced in contact sport, does not cause significant, direct damage to skeletal muscle. However, the relationship between oedema volume, changes in pressure pain threshold and maximum voluntary contraction force suggests central inhibition plays a role in contusion-related muscle dysfunction.