Actual and perceived motor competence mediate the relationship between physical fitness and technical skill performance in young soccer players.

This study examined the role of fundamental movement skills (FMS) and perceived competence in the relationship between physical fitness and technical soccer skills in children. Seventy boys aged 7-12 years of age (Mean ± SD = 9 ± 2 years) who were regularly engaged in grassroots soccer participated in the present study. The Test of Gross Motor Development-2 (Ulrich, 2001. Test of gross motor development (2nd ed.). Austin, TX: PRO-ED) was used to assess FMS and the Perceived Physical Ability Scale for Children (Colella, Morano, Bortoli, & Robazza, 2008. A physical self-efficacy scale for children. Social Behavior and Personality: an International Journal, 36, 841-848) was used to assess perceived competence. Technical skill was determined from three tests reflecting dribbling, passing and shooting. Z-scores of each measure were summed, creating a composite measure of technical skill. Three measures of physical fitness were employed; 15m sprint time, standing long jump, and seated medicine ball (1kg) throw. Z-scores for each measure were summed creating a composite measure of physical fitness. The relationship between technical skill and FMS, fitness, perceived competence and age was examined via path analysis. Results indicated two significant mediated pathways: from physical fitness to technical skills via FMS, and from physical fitness to technical skills via perceived competence. Once these mediators had been accounted for, there was no direct link from physical fitness to technical skills. Coaches should therefore seek to avoid one-sided delivery of practice by not solely focusing on football type drills, and focusing on a range of activities which enhance a broad foundation of FMS and promote strategies to positively influence a child's perception of their own competence.HighlightsFundamental movement skills (FMS) are considered the foundation for physical activity and sport performance yet they tend to be overlooked, in favour of physical fitness, in the development of soccer talent.We examined mediating effects of FMS and perceived competence in the relationship between physical fitness and technical soccer skills in 70, 7-12 year old grassroots soccer players.We suggests there is no direct effect of physical fitness on technical skills in soccer but both FMS and perceived competence act as mediators of the physical fitness-technical skill relationship in children aged 7-12 years old.Coaches should therefore look to develop a broad base of FMS and a higher perception of competence to improve children's technical soccer skills.

A systematic review of the role of heat therapy for patients with intermittent claudication due to peripheral artery disease.

Intermittent claudication (IC) is associated with impairments in quality of life and walking ability. Heat therapy is an emerging cardiovascular therapy, which may improve walking in patients with IC. We undertook a systematic review to establish current evidence for heat therapy for patients with IC. We searched five databases (Ovid Medline / PubMed, Embase, Scopus / Web of Science, Cochrane Library and Health Technology Assessment Databases). A total of 6751 records were screened with 76 full-text articles assessed for eligibility. We included three randomised control trials and three acute interventions. For chronic interventions, three different heat therapy interventions were used. The 6-minute walk distance significantly improved following whole-body immersion (p = 0.03; ES 0.94, 95% CI: 0.06-1.82), but not after Waon therapy or a water-perfused garment. Ankle-brachial pressure indices were significantly improved following whole-body immersion (p = 0.01; ES 1.10, 95% CI: 0.20-1.99) but not after other therapies. No form of heat therapy demonstrated statistical improvements in quality of life or brachial blood pressure. Acute interventions were characterised by large increases in limb blood flow and core temperature, and transient reductions in blood pressure post-heating. At present there are only three randomised controlled trials assessing heat therapy for patients with IC. Moreover, each of those randomised controlled trials utilised different heat therapies. There is also very limited study of the acute physiological responses to different heat therapy interventions in these populations. Future research should establish appropriate heat therapy protocols and implement more randomised trials to understand its effectiveness. PROSPERO: CRD42020187941.

A comparison of the metabolic effects of sustained strenuous activity in polar environments on men and women.

This study investigates differences in pre- to post-expedition energy expenditure, substrate utilisation and body composition, between the all-male Spear17 (SP-17) and all-female Ice Maiden (IM) transantarctic expeditions (IM: N = 6, 61 days, 1700 km; SP-17: N = 5, 67 days, 1750 km). Energy expenditure and substrate utilisation were measured by a standardised 36 h calorimetry protocol; body composition was determined using air displacement plethysmography. Energy balance calculation were used to assess the physical challenge. There was difference in the daily energy expenditure (IM: 4,939 kcal day-1; SP-17: 6,461 kcal day-1, p = 0.004); differences related to physical activity were small, but statistically significant (IM = 2,282 kcal day-1; SP-17 = 3,174 kcal day-1; p = 0.004). Bodyweight loss was modest (IM = 7.8%, SP-17 = 6.5%; p > 0.05) as was fat loss (IM = 30.4%, SP-17 = 40.4%; p > 0.05). Lean tissue weight change was statistically significant (IM = - 2.5%, SP-17 = + 1.0%; p = 0.05). No difference was found in resting or sleeping energy expenditure, normalised to lean tissue weight (p > 0.05); nor in energy expenditure when exercising at 80, 100 and 120 steps min-1, normalised to body weight (p > 0.05). Similarly, no difference was found in the change in normalised substrate utilisation for any of the activities (p > 0.05). Analysis suggested that higher daily energy expenditures for the men in Spear-17 was the result of higher physical demands resulting in a reduced demand for energy to thermoregulate compared to the women in Ice Maiden. The lack of differences between men and women in the change in energy expenditure and substrate utilisation, suggests no sex difference in response to exposure to extreme environments.

Metabolic rate and substrate utilisation resilience in men undertaking polar expeditionary travel.

The energy expenditure and substrate utilisation were measured in 5 men pre- and post- a 67 day, 1750km unassisted Antarctic traverse from the Hercules Inlet to the Ross Sea Ice via the South pole pulling sledges weighing 120kg whilst experiencing temperatures as low as -57°C. A 36-hours protocol in a whole body calorimeter was employed to measure periods of rest, sleep and three periods of standardised stepping exercises at 80, 100 and 120 steps min-1; participants were fed isocalorically. Unlike previous expeditions where large weight loss was reported, only a modest loss of body weight (7%, P = 0.03) was found; fat tissue was reduced by 53% (P = 0.03) together with a small, but not statistically significant, increase in lean tissue weight (P = 0.18). This loss occurred despite a high-energy intake (6500 kcal/day) designed to match energy expenditure. An energy balance analysis suggested the loss in body weight could be due to the energy requirements of thermoregulation. Differences in energy expenditure [4.9 (0.1) vs 4.5 (0.1) kcal/min. P = 0.03], carbohydrate utilisation [450 (180) vs 569 (195) g/day; P = 0.03] and lipid utilisation [450 (61) vs 388 (127) g/day, P = 0.03] at low levels of exertion were different from pre-expedition values. Only carbohydrate utilisation remained statistically significant when normalised to body weight. The differences in energy expenditure and substrate utilisation between the pre- and post-expedition for other physiological states (sleeping, resting, higher levels of exercise, etc) were small and not statistically significant. Whilst inter-subject variability was large, there was a tendency for increased carbohydrate utilisation, post-expedition, when fasted that decreased upon feeding.

Female Reproductive, Adrenal, and Metabolic Changes during an Antarctic Traverse.

PURPOSE: To explore the effects of the first all-female transantarctic expedition on hormonal axes pertinent to reproductive and metabolic function. METHODS: Six females (age, 28-36 yr; body mass index, 24.2 ± 0.97 kg·m) hauled 80-kg sledges 1700 km in 61 d. Estimated average energy intake was 20.8 ± 0.1 MJ·d (4970 ± 25 kcal·d). Whole and regional body composition was measured by dual-energy x-ray absorptiometry 1 and 2 months before and 15 d after, the expedition. Body fat was also estimated by skinfold and bioimpedance immediately before and after the expedition. Basal metabolic and endocrine blood markers and, after 0.25 mg dexamethasone suppression, 1-h 10-µg gonadorelin and 1.0 µg adrenocortiocotrophin-(1-24) tests were completed, 39-38 d preexpedition and 4 to 5 d and 15 to 16 d postexpedition. Cortisol was assessed in hair (monthly average concentrations) and saliva (five-point day curves and two-point diurnal sampling). RESULTS: Average body mass loss was 9.37 ± 2.31 kg (P < 0.0001), comprising fat mass only; total lean mass was maintained. Basal sex steroids, corticosteroids, and metabolic markers were largely unaffected by the expedition except leptin, which decreased during the expedition and recovered after 15 d, a proportionately greater change than body fat. Luteinizing hormone reactivity was suppressed before and during the expedition, but recovered after 15 d, whereas follicle-stimulating hormone did not change during or after the expedition. Cortisol reactivity did not change during or after the expedition. Basal (suppressed) cortisol was 73.25 ± 45.23 mmol·L before, 61.66 ± 33.11 mmol·L 5 d postexpedition and 54.43 ± 28.60 mmol·L 16 d postexpedition (P = 0.7). Hair cortisol was elevated during the expedition. CONCLUSIONS: Maintenance of reproductive and hypothalamic-pituitary-adrenal axis function in women after an extreme physical endeavor, despite energy deficiency, suggests high female biological capacity for extreme endurance exercise.

Pre- to postexpedition changes in the energy usage of women undertaking sustained expeditionary polar travel.

This paper reports the metabolic energy changes in six women who made the first unsupported traverse of Antarctica, covering a distance of 1,700 km in 61 days, hauling sledges weighing up to 80 kg. Pre- and postexpedition, measurements of energy expenditure and substrate utilization were made on all six members of the expedition over a 36-h period in a whole body calorimeter. During the study, subjects were fed an isocaloric diet: 50% carbohydrate, 35% fat, and 15% protein. The experimental protocol contained pre- and postexpedition measurement, including periods of sleep, rest, and three periods of standardized stepping exercise at 80, 100, and 120 steps/min. A median (interquartile range) decrease in the lean and fat weight of the subjects of 1.4 (1.0) and 4.4 (1.8) kg, respectively (P < 0.05) was found, using air-displacement plethysmography. No statistically significant difference was found between pre- and postexpedition values for sleeping or resting metabolic rate, nor for diet-induced thermogenesis. A statistically significant difference was found in energy expenditure between the pre- and postexpedition values for exercise at 100 [4.7 (0.23) vs. 4.4 (0.29), P < 0.05] and 120 [5.7 (0.46) vs. 5.5 (0.43), P < 0.05] steps/min; a difference that disappeared when the metabolic rate values were normalized to body weight. The group was well matched for the measures studied. Whereas a physiological change in weight was seen, the lack of change in metabolic rate measures supports a view that women appropriately nourished and well prepared can undertake polar expeditions with a minimal metabolic energy consequence. NEW & NOTEWORTHY This is the first study on the metabolic energy consequences for women undertaking expeditionary polar travel. The results show that participant selection gave a "well-matched" group, particularly during exercise. Notwithstanding this, individual differences were observed and explored. The results show that appropriately selected, trained, and nourished women can undertake such expeditions with no change in their metabolic energy requirements during rest or while undertaking moderate exercise over a sustained period of time.