Effects of load mass carried in a backpack upon respiratory muscle fatigue.

The purpose of this study was to investigate whether loads carried in a backpack, with a load mass ranging from 0 to 20 kg, causes respiratory muscle fatigue. Methods: Eight males performed four randomised load carriage (LC) trials comprising 60 min walking at 6.5 km h−1 wearing a backpack of either 0 (LC0), 10 (LC10), 15 (LC15) or 20 kg (LC20). Inspiratory (PImax) and expiratory (PEmax) mouth pressures were assessed prior to and immediately following each trial. Pulmonary gas exchange, heart rate (HR), blood lactate and glucose concentration and perceptual responses were recorded during the first and final 60 s of each trial. Results: Group mean PImax and PEmax were unchanged following 60-min load carriage in all conditions (p > .05). There was an increase over time in pulmonary gas exchange, HR and perceptions of effort relative to baseline measures during each trial (p  .05). Conclusions: These findings indicate that sub-maximal walking with no load or carrying 10, 15 or 20 kg in a backpack for up to 60 min does not cause respiratory muscle fatigue despite causing an increase in physiological, metabolic and perceptual parameters.N/

Whole body active warm up and inspiratory muscle warm up do not improve running performance when carrying thoracic loads

Whole body active warm ups (AWU) and inspiratory muscle warm up (IMW) prior to exercise improves performance on some endurance exercise tasks. This study investigated the effects of AWU with and without IMW upon 2.4 km running time-trial performance while carrying a 25 kg backpack, a common task and backpack load in physically demanding occupations. Participants (n = 9) performed five 2.4 km running time-trials with a 25 kg thoracic load preceded in random order by 1) IMW comprising 2 x 30 inspiratory efforts against a pressure-threshold load of 40 % maximal inspiratory pressure (PImax), 2) 10 min unloaded running (AWU) at lactate turnpoint (10.33 ± 1.58 km·h-1), 3) placebo IMW (PLA) comprising five min breathing using a sham device, 4) AWU+IMW and 5) AWU+PLA. Pooled baseline PImax was similar between trials and increased by 7% and 6% following IMW and AWU+IMW (P0.05). Time-trial performance was not different between any trials. Whole body AWU and IMW performed alone or combination have no ergogenic effect upon high intensity, short duration performance when carrying a 25 kg load in a backpack.N/

PRE-COVID-19 PHYSICAL ACTIVITY STATUS DOES NOT PROTECT AGAINST REDUCTIONS IN POST-COVID-19 SYMPTOMS: A CORRELATION RELATIVISTIC ANALYSIS DURING THE LOCKDOWN

People who exhibit unhealthy lifestyle behaviours are at greater risk of severe disease outcomes, risk of hospitalisation and mortality when infected with COVID-19. Accordingly, it is suggested that those with higher levels of cardiorespiratory fitness and who engage in regular physical activity (PA) are associated with a reduced risk of adverse outcomes. Although improved physiological function may protect individuals against severe acute COVID-19 outcomes, it is unknown whether it offers protection against developing sustained symptom profile, known as post-acute COVID-19 syndrome or Long COVID. Affecting an estimated 2 million people in the UK and 144 million globally, Long COVID is challenging healthcare services with broader social and economic impacts. Accordingly, this project aimed to determine the impact of PA status on Long COVID. An online survey was developed Utilizing adapted versions of preexisting Patient Re-ports Outcome Measures (Qualtrics, Provo, Utah, United States). Participants self-reported PA status in line with the World Health Organisation guidelines and their pre- and post-COVID-19 health status and symptom profile. A Mann-Whitney U test was used to analyse between-group responses, and a Wilcoxon Signed Rank test was used to analyse within-group responses. The survey was completed by 381 participants, of which n=253 reported meeting or exceeding the recommended guidelines of PA. A significant difference was found between pre- and post-COVID-19 health, whilst a Mann-Whitney U test concluded that there was no significant difference between PA groups and post-COVID-19 health status. According to the results, increased PA and cardiorespiratory fitness might offer protection against severe disease outcomes in the acute phase of infection but this does not offer full protection against developing a long-term symptom profile and increased mechanistic understanding of the physiological determinants is needed to restore the pre-COVID-19 status and assist in the development of multi-disciplinary interventions.  Article visualizations

The Effects of a Nutrition Education Intervention on Sports Nutrition Knowledge during a Competitive Season in Highly Trained Adolescent Swimmers

The aim of this study was to evaluate the effects of a seven-week nutrition education intervention on the sports nutrition knowledge (SNK) of highly trained UK adolescent swimmers. Fifteen national and international adolescent swimmers (males = 5; females = 10, 15.5 ± 1.1 years, 170.2 ± 7.5 cm, 60.3 ± 5.7 kg) participated in the study during seven consecutive weeks of the competitive swimming season. The participants received 30 min of nutrition education once per week in a classroom-based setting after they had completed their regular swim training. An undergraduate sports nutrition student delivered all nutrition education sessions and SNK questionnaires were administered to the participants pre- and post-intervention. The mean total SNK score improved by 8.3% (SD = 8.4%, 95% CI = 4.1–12.6; p = 0.006; ES = 1.0) following the nutrition education sessions. On an individual basis, ten swimmers significantly improved their total SNK score, whereas four swimmers did not improve, and one swimmer performed significantly worse after the intervention. Moreover, the swimmers’ knowledge of hydration improved by 22.2% (SD = 20.6%, 95% CI = 11.8–32.6, p = 0.004, ES = 1.1) over the seven-week timeframe, which was the only nutrition topic to have a significantly increased knowledge score. The current study therefore suggests that a nutrition education intervention can positively influence the SNK of highly trained adolescent swimmers

Calibration and Cross-Validation of Accelerometery for Estimating Movement Skills in Children Aged 8-12 Years

This study sought to calibrate triaxial accelerometery, worn on both wrists, waist and both ankles, during children’s physical activity (PA), with particular attention to object control motor skills performed at a fast and slow cadence, and to cross-validate the accelerometer cut-points derived from the calibration using an independent dataset. Twenty boys (10.1 ±1.5 years) undertook seven, five-minute bouts of activity lying supine, standing, running (4.5kmph−1) instep passing a football (fast and slow cadence), dribbling a football (fast and slow cadence), whilst wearing five GENEActiv accelerometers on their non-dominant and dominant wrists and ankles and waist. VO2 was assessed concurrently using indirect calorimetry. ROC curve analysis was used to generate cut-points representing sedentary, light and moderate PA. The cut-points were then cross-validated using independent data from 30 children (9.4 ± 1.4 years), who had undertaken similar activities whilst wearing accelerometers and being assessed for VO2. GENEActiv monitors were able to discriminate sedentary activity to an excellent level irrespective of wear location. For moderate PA, discrimination of activity was considered good for monitors placed on the dominant wrist, waist, non-dominant and dominant ankles but fair for the non-dominant wrist. Applying the cut-points to the cross-validation sample indicated that cut-points validated in the calibration were able to successfully discriminate sedentary behaviour and moderate PA to an excellent standard and light PA to a fair standard. Cut-points derived from this calibration demonstrate an excellent ability to discriminate children’s sedentary behaviour and moderate intensity PA comprising motor skill activity.N/

Multi-component physical activity interventions in the UK must consider determinants of activity to increase effectiveness

Interventions to increase physical activity in children have adopted broad approaches and achieved varying success. There is a need to adopt approaches underpinned with a theoretical basis. Accordingly, the aim here was to implement and evaluate a 12-week intervention designed using the concepts of the COM-B model to determine the effect this has on physical activity levels. One hundred and forty-seven school-age children (mean age 8.9 ± 1.3 years) took part in a 12-week program delivered in a school setting. Topics included physical activity, healthy eating, sleep quality and reducing screen time/sedentary activities when not in school. A sample of participants wore a wrist-worn accelerometer for seven days pre-and post-intervention (N = 11). The physical activity frequency was unchanged (2.9 ± 1.0 AU) when compared with post-intervention values (3.1 ± 0.8 AU, mean increase 6.8 ± 3.7%, p > 0.05). Changes were observed in the daily consumption of fruit and vegetables (pre-intervention 44.6% vs. post-intervention 60.2%, p p > 0.05). There is a need to adopt a broader approach that incorporates a theoretical basis and considers the complex ways by which physical activity behaviours are influenced

Sodium Bicarbonate Ingestion Improves Time-to-Exhaustion Cycling Performance and Alters Estimated Energy System Contribution:A Dose-Response Investigation

This study investigated the effects of two sodium bicarbonate (NaHCO3) doses on estimated energy system contribution and performance during an intermittent high-intensity cycling test (HICT), and time-to-exhaustion (TTE) exercise. Twelve healthy males (stature: 1.75 ± 0.08 m; body mass: 67.5 ± 6.3 kg; age: 21.0 ± 1.4 years; maximal oxygen consumption: 45.1 ± 7.0 ml.kg.min-1) attended four separate laboratory visits. Maximal aerobic power (MAP) was identified from an incremental exercise test. During the three experimental visits, participants ingested either 0.2 g.kg-1 BM NaHCO3 (SBC2), 0.3 g.kg-1 BM NaHCO3 (SBC3), or 0.07 g.kg-1 BM sodium chloride (placebo; PLA), 60 minutes pre-exercise. The HICT involved 3 x 60 s cycling bouts (90%, 95%, 100% MAP) interspersed with 90 s recovery, followed by TTE cycling at 105% MAP. Blood lactate was sampled after each cycling bout to calculate estimates for glycolytic contribution to exercise. Gastrointestinal (GI) upset was quantified at baseline, 30 minutes and 60 minutes post-ingestion, and 5 minutes post-exercise. Cycling TTE increased for SBC2 (+20.2 s; p =0.045) and SBC3 (+31.9 s; p =0.004) compared to PLA. Glycolytic contribution increased during the TTE protocol for SBC2 (+7.77 kJ; p =0.10) and SBC3 (+7.95 kJ; p =0.07) compared to PLA. GI upset was exacerbated post-exercise after SBC3 for nausea compared to SBC2 and PLA (p 0.05). Both NaHCO3 doses enhanced cycling performance and glycolytic contribution, however, higher doses may maximise ergogenic benefits

Training the inspiratory muscles improves running performance when carrying a 25 kg thoracic load in a backpack.

Load carriage (LC) exercise in physically demanding occupations is typically characterised by periods of low-intensity steady-state exercise and short duration, high-intensity exercise while carrying an external mass in a backpack; this form of exercise is also known as LC exercise. This induces inspiratory muscle fatigue and reduces whole-body performance. Accordingly we investigated the effect of inspiratory muscle training (IMT, 50% maximal inspiratory muscle pressure (PImax) twice daily for six week) upon running time-trial performance with thoracic LC. Nineteen healthy males formed a pressure threshold IMT (n = 10) or placebo control group (PLA; n = 9) and performed 60 min LC exercise (6.5 km h(-1)) followed by a 2.4 km running time trial (LCTT) either side of a double-blind six week intervention. Prior to the intervention, PImax was reduced relative to baseline, post-LC and post-LCTT in both groups (pooled data: 13 ± 7% and 16 ± 8%, respectively, p  .05). In IMT only, heart rate and perceptual responses were reduced post-LC (p < .05). Time-trial performance was unchanged post-PLA and improved 8 ± 4% after IMT (p < .05). In summary, when wearing a 25 kg backpack, IMT attenuated the cardiovascular and perceptual responses to steady-state exercise and improved high-intensity time-trial performance which we attribute in part to reduced relative work intensity of the inspiratory muscles due to improved inspiratory muscle strength. These findings have real-world implications for occupational contexts.N/

Feasibility, psychosocial effects, influence, and perception of elastic band resistance balance training in older adults

This study utilised feedback from older adults during balance-challenging, elastic band resistance exercises to design a physical activity (PA) intervention. Methods: Twenty-three active participants, aged 51 – 81 years, volunteered to perform a mini balance evaluation test and falls efficacy scale, and completed a daily living questionnaire. Following a 10 min warm-up, participants performed eight pre-selected exercises (1 × set, 8 – 12 repetitions) using elastic bands placed over the hip or chest regions in a randomised, counterbalanced order with 15 min seated rests between interventions. Heart rate (HR) and rate of perceived exertion (RPE) were measured throughout. Participant interview responses were used to qualify the experiences and opinions of the interventions including likes, dislikes, comfort, and exercise difficulty. Results: Similar significant (p \u3c 0.01) increases in HR (pre- = 83 – 85 bpm, mid- = 85 – 88 bpm, post-intervention = 88 – 89 bpm; 5 – 6 %) and RPE (pre- = 8 – 9, mid- = 10, post-intervention = 10 – 11) were detected during the PA interventions (hip and chest regions). Interview data revealed that participants thought the PA interventions challenged balance, that the exercises would be beneficial for balance, and that the exercises were suitable for themselves and others. Participants reported a positive experience when using the PA interventions with an elastic band placed at the hip or chest and would perform the exercises again, preferably in a group, and that individual preference and comfort would determine the placement of the elastic band at either the hip or chest. Conclusion: These positive outcomes confirm the feasibility of a resistance band balance program and will inform intervention design and delivery in future studies

Preloaded time trial to assess load carriage performance.

The relevance and importance of load carriage in recreational and occupational tasks has stimulated a large body of research. Exercise protocols have been criticized for a lack of relevance to occupational activities; accordingly, the aim of this study was to assess the reliability of a preloaded time-trial protocol for load carriage assessment. After full familiarization, 8 healthy males performed 2 trials separated by 1 week. Each trial comprised 60-minute walking at 6.5 km·h and 0% gradient (LC), 15 minutes seated recovery followed by a 2.4-km time-trial (LCTT). All trials were performed wearing a 25-kg backpack. Performance time was 16.71 ± 1.82 minutes and 16.37 ± 1.78 minutes for LCTT 1 and 2, respectively with a mean difference of -0.34 ± 0.89 minutes. Using log ratio limits of agreement, the mean bias was 1.02 and random error component of the agreement ratio was 1.11. The intraclass correlation was 0.85, coefficient of variation was 10.5%, and Cohen's d was 0.35. The protocol demonstrated a very good level of reliability. We present a novel and reliable preloaded time-trial protocol that more closely reflects operational activities and can be used to quantify load carriage performance. This protocol provides greater ecologically validity regarding physical demands of load carriage activities than those adopted previously and provides an excellent tool for the strength and conditioning practitioner to assess individual load carriage performance.N/