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Volume 32 (2024): Issue 3 (Jun 2024)

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Volume 18 (2024): Issue 2 (Jun 2024)

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Myths and Methodologies: Standardisation in Human Physiology Research—Should We Control the Controllables?

Lucy H. Merrell, Oliver J. Perkin, Louise Bradshaw, Harrison D. Collier-Bain, Adam J. Collins, Sophie Davies, Rachel Eddy, James A. Hickman, Anna P. Nicholas, Daniel Rees, Bruno Spellanzon, Lewis J. James, Alannah K.A. McKay, Harry A. Smith, James E. Turner, Francoise Koumanov, Jennifer Maher, Dylan Thompson, Javier T. Gonzalez, and James A. Betts

The premise of research in human physiology is to explore a multifaceted system whilst identifying one or a few outcomes of interest. Therefore, the control of potentially confounding variables requires careful thought regarding the extent of control and complexity of standardisation. One common factor to control prior to testing is diet, as food and fluid provision may deviate from participants’ habitual diets, yet a self-report and replication method can be flawed by under-reporting. Researchers may also need to consider standardisation of physical activity, whether it be through familiarisation trials, wash-out periods, or guidance on levels of physical activity to be achieved before trials. In terms of pharmacological agents, the ethical implications of standardisation require researchers to carefully consider how medications, caffeine consumption and oral contraceptive prescriptions may affect the study. For research in females, it should be considered whether standardisation between- or within-participants in regards to menstrual cycle phase is most relevant. The timing of measurements relative to various other daily events is relevant to all physiological research and so it can be important to standardise when measurements are made. This review summarises the areas of standardisation which we hope will be considered useful to anyone involved in human physiology research, including when and how one can apply standardisation to various contexts.

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Cadence Paradox in Cycling—Part 2: Theory and Simulation of Maximal Lactate Steady State and Carbohydrate Utilization Dependent on Cycling Cadence

Ralph Beneke and Renate M. Leithäuser

Purpose: To develop and evaluate a theory on the frequent observation that cyclists prefer cadences (RPMs) higher than those considered most economical at submaximal exercise intensities via modeling and simulation of its mathematical description. Methods: The theory combines the parabolic power-to-velocity (v) relationship, where v is defined by crank length, RPM-dependent ankle velocity, and gear ratio, RPM effects on the maximal lactate steady state (MLSS), and lactate-dependent carbohydrate oxidation (CHO). It was tested against recent experimental results of 12 healthy male recreational cyclists determining the v-dependent peak oxygen uptake (VO 2PEAKv ), MLSS (MLSS v ), corresponding power output (P MLSSv ), oxygen uptake at P MLSSv (VO 2MLSSv ), and CHO MLSSv -management at 100 versus 50 per minute, respectively. Maximum RPM (RPM MAX ) attained at minimized pedal torque was measured. RPM-specific maximum sprint power output (P MAXv ) was estimated at RPMs of 100 and 50, respectively. Results: Modeling identified that MLSS v and P MLSSv related to P MAXv (IP MLSSv ) promote CHO and that VO 2MLSSv related to VO 2PEAKv inhibits CHO. It shows that cycling at higher RPM reduces IP MLSSv . It suggests that high cycling RPMs minimize differences in the reliance on CHO at MLSS v between athletes with high versus low RPM MAX . Conclusions : The present theory-guided modeling approach is exclusively based on data routinely measured in high-performance testing. It implies a higher performance reserve above IP MLSSv at higher RPM. Cyclists may prefer high cycling RPMs because they appear to minimize differences in the reliance on CHO at MLSS v between athletes with high versus low RPM MAX .

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Effect of 6-Week Sprint Training on Long-Distance Running Performance in Highly Trained Runners

Ryosuke Ando, Chihiro Kojima, Saya Okamoto, Nobukazu Kasai, Daichi Sumi, Kenji Takao, Kazushige Goto, and Yasuhiro Suzuki

Purpose : Long-distance running performance has been reported to be associated with sprint performance in highly trained distance runners. Therefore, we hypothesized that sprint training could enhance distance running and sprint performance in long-distance runners. This study examined the effect of 6-week sprint training on long-distance running and sprint performance in highly trained distance runners. Methods : Nineteen college runners were divided into control (n = 8) and training (n = 11) groups. Participants in the training group performed 12 sprint training sessions in 6 weeks, while those in the control group performed 12 distance training sessions. Before and after the interventions, maximal oxygen uptake ( V ˙ O 2 max ), O2 cost during submaximal running (290 m·min−1 and 310 m·min−1 of running velocity), and time to exhaustion (starting at 290 m·min–1 and increased 10 m·min–1 every minute) were assessed on a treadmill. Additionally, the 100-m and 400-m sprinting times and 3000-m running time were determined on an all-weather track. Results : In the control group, no measurements significantly changed after the intervention. In the training group, the time to exhaustion, 100-m and 400-m sprinting times, and 3000-m running time improved significantly, while V ˙ O 2 max and O2 cost did not change. Conclusions : These results showed that 6-week sprint training improved both sprint and long-distance running performance in highly trained distance runners without a change in aerobic capacity. Improvement in the time to exhaustion without a change in V ˙ O 2 max suggests that the enhancement of long-distance running performance could be attributable to improved anaerobic capacity.

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Habitual Nocturnal Sleep, Napping Behavior, and Recovery Following Training and Competition in Elite Water Polo: Sex-Related Effects

Nickos G. Koutouvakis, Nickos D. Geladas, Athanasios Mouratidis, Argyris G. Toubekis, and Petros G. Botonis

Purpose: To examine nocturnal sleep patterns, napping behaviors, and subjective wellness responses of elite water polo players within an in-season week and to identify whether sleeping patterns differ between men and women. Methods: Sleep characteristics of 10 male and 17 female professional water polo players were objectively assessed during 1 week of the in-season period, including 5 training days, 1 match day, and 1 day of rest. Internal load (rating of perceived exertion × duration of training or match) was assessed 30 minutes posttraining or postmatch, and the total quality of recovery was recorded every morning. A series of multilevel models were used to analyze the data. Results: Time in bed and wake-up time were earlier on both training (P < .001) and rest days (P < .001) than on the day of the match. Internal workload did not predict any of the players’ sleeping patterns. Midday naps predicted less time in bed (P = .03) and likely less sleep time (P = .08). The total quality of recovery was predicted only by the total sleep time (P < .01). Women exhibited higher sleep efficiency (P < .001), less waking after sleep onset (P = .01), and a lower number of awakenings (P = .02) than men. Conclusions: The current results indicate that the nocturnal sleep patterns of elite water polo players are not associated with internal load and that women display better nocturnal sleep quality compared with men. As long naps interfere with nocturnal sleep, and total nocturnal sleep time predicts total quality of recovery, we suggest that athletes follow hygiene sleep strategies to facilitate adequate nocturnal sleep and next-day recovery.

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Monitoring Within-Individual Dose–Response Relationships in Professional Soccer Players: The Importance of Fitness Level

Alireza Rabbani, Giorgios Ermidis, Filipe Manuel Clemente, and Liam Anderson

Purpose: To (1) examine within-individual player dose–response associations between selected training-load measures and changes in aerobic fitness level via submaximal exercise heart rate (HRex%) and (2) measure the relationships between these dose–response associations with basal HRex% (to study the influence of fitness level on dose–response relationship). Methods: During an in-season phase, selected training-load measures including total minutes, total distance, mechanical work (the sum number of accelerations and decelerations > 3 m2), high metabolic load distance, and Edwards’ training impulse were collected via Global Positioning System and heart-rate sensors for analyzing accumulated load. A submaximal warm-up test was used repeatedly before and after 9 phases to elicit HRex% and track fitness changes at an individual level. Results: Negative to positive extensive ranges of within-individual associations were found among players for different metrics (r = −.84 to .89). The relationship between pooled HRex% (basal fitness) and dose–response correlations showed inverse very large (r = −.71) and large (r = −.65) values for accumulated weekly minutes and distance. However, moderate values were found for all other measures (r = −.35 to −.42). Conclusions: Individual players show extensive different ranges of dose–response associations with training measures. The dose–response association is influenced by players’ fitness level, and players with lower fitness levels show stronger inverse relationships with accumulated minutes and total distance.

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Swim, Strength, or Combined Programs: Effect on Health-Related Physical Fitness in Adolescents With Down Syndrome

Borja Suarez-Villadat, Kabir Sadarangani, Rui Manuel Corredeira, Mario Veiga, and Ariel Villagra

The adolescent population with Down syndrome (DS) appears to show higher levels of body fat and lower levels of cardiorespiratory fitness or muscle strength than their peers without disabilities. There is a need to create physical activity programs to improve these data. The aim of this research was to determine the effects of a 16-week swimming program, strength program, and combined program (swimming and strength training) on body composition and health-related physical fitness on adolescents with DS and to assess whether there are differences in the results of the different training programs. Forty-five adolescents (17 female and 28 male; average age 15.5 [1.53] years) with DS were recruited and randomized to three groups (swim [n = 15], strength [n = 15], and combined [n = 15]). Results showed that the swim group had significant improvements in all health-related physical fitness variables and there was an improvement in some body-composition variables (p < .05). The strength and combined groups obtained minor improvements in the variables analyzed. In summary, a 16-week swim program consisting of three sessions of 60 min is able to improve levels of body composition and health-related physical fitness in adolescents with DS. The swim training program seems to be more effective in improving body composition and health-related physical fitness than the strength or combined program. These findings could be useful in different special-education centers due to the predisposition shown by the population with DS to this sport modality.

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Effect of Protein Supplementation Combined With Resistance Training in Gait Speed in Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Juan Li, Yahai Wang, Fang Liu, and Yu Miao

Background: We aimed to evaluate the effectiveness of the combination of protein supplementation and resistance training (RT), compared with RT alone or combined with a placebo, in improving gait speed. Methods: We searched PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases, and 18 randomized controlled trials with 1,147 older participants were included for meta-analysis. Data were pooled as the effect sizes (Hedges’ g) with 95% confidence interval (CI) of the gait speed (in meters per second). The random-effect meta-analysis, subgroup analyses, meta-regression, and sensitivity analysis were conducted. Results: The combination of protein supplementation and RT significantly improved gait speed (Hedges’ g: 0.52 m/s, 95% confidence interval [0.17, 0.86], p = .005; I 2  = 86.5%) compared with the RT alone. The subgroup analyses revealed that the significant improvement in gait speed postprotein intervention plus RT was observed only in participants who consumed protein after RT (Hedges’ g: 0.90 m/s, 95% confidence interval [0.46, 1.33], p = .001; I 2  = 79.6%). The pooled result did not significantly change after excluding any single study at one time or excluding smaller studies with large effect sizes. Conclusions: Protein supplementation combined with RT could significantly improve the gait speed of older adults compared with RT alone. This positive effect is more pronounced in people who consume protein after RT.

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“Now I Am Walking Toward Health”: A Qualitative Study About the Outcomes of Physical Activity Participation That Matter to Older Adults

Peter J. Young, Christine Wallsworth, Hitika Gosal, and Dawn C. Mackey

Background/Objectives: Randomized controlled trials that deliver physical activity interventions have demonstrated benefits for older adults across numerous health outcomes. However, too little attention has been directed to ensuring that such trials are measuring patient-relevant outcomes. To support outcome selection for future trials, the objective of this study was to understand what outcomes related to their physical activity participation older adults find important. Methods: We conducted 12 semistructured interviews with adults aged 65 years and older and analyzed interview transcripts with a reflexive thematic analysis. Results: Older adults desired diverse outcomes from their physical activity participation, ranging from generic (e.g., quality of life) to specific (e.g., leg strength). Relevant outcomes were classified under five themes: physical, clinical, social, psychological, and overarching, each with respective subthemes. Conclusions: The outcomes that older adults found important were plentiful and rooted in a desire to improve their quality of life. Some of the outcome themes have been reported frequently in past trials (e.g., physical), but others have not (e.g., social). Future researchers should be aware of, and responsive to, the priorities of older adults when designing trials and defining outcomes. Significance/Implications: This study will help to improve outcome selection for future trials of physical activity with older adults. In alignment with a patient-oriented research philosophy, this study will also ground future outcome selection in the priorities of older adults.