High-intensity demands of 6-a-side small-sided games and 11-a-side matches in youth soccer players

Purpose. The purposes of the present study were to examine: high-intensity running distance during 6-a-side small-sided games (SSGs) and 11-a-side matches (11M) in youth soccer players using speed and metabolic power approaches and; the magnitude of difference between high-intensity running distance calculated with the two approaches. Method. Eleven outfield players (age = 16.3 ± 0.6 years) performed SSGs with three pitch sizes (small SSG (SSGS), medium SSG (SSGM) and large SSG (SSGL)) and 11M. A Global Positioning System (15 Hz) was employed to calculate total distance covered, distance covered at a speed ≥ 4.3 m∙s-1 (TS) and metabolic power of ≥ 20 W·kg-1 (TP). Results. The total distance covered increased from SSGS through to SSGL (P < 0.001) and was greater during 11M and SSGL compared to other SSGs (P < 0.01). TS and TP increased from SSGS (TS vs. TP = 98 ± 55 vs. 547 ± 181 m) through to SSGL (538 ± 167 vs. 1050 ± 234 m, P < 0.001). TS and TP during 11M (370 ± 122 vs. 869 ± 233 m) was greater than SSGS (P < 0.001 for both) and less than SSGL (P < 0.05 for both). The magnitude of difference between TS and TP (%) reduced with an increase in pitch size during SSGs and was greater in SSGS (615 ± 404%, P < 0.001) and SSGM (195 ± 76%, P < 0.05) and smaller in SSGL (102 ± 33%, P < 0.01) compared to 11M (145 ± 53%). Conclusion. SSGs can replicate the high-intensity demands of 11M and the speed approach underestimates high-intensity demands of SSGs and 11M compared to the metabolic power approach

Role of physical activity in regulating appetite and body fat

Recent articles in the press have questioned the role of physical activity in regulating appetite and controlling bodyweight. These articles can be confusing and misleading for the public. Yet this is a complex area and there is disagreement about the importance of physical activity even among academics. Uncertainty and misunderstanding in this area may be related to the heterogeneity of the term ‘physical activity’ which encompasses sporting pursuits with extremely high levels of energy expenditure over prolonged periods of time, as well as everyday tasks involving much lower levels of energy expenditure on an intermittent basis. This latter form of physical activity includes what has been termed ‘non-exercise activity thermogenesis’ (NEAT). In the right circumstances, physical activity can make a major contribution to the maintenance of a healthy weight even in the absence of dietary control although a combination of the two is almost certain to be more effective. In the long-term, evidence suggests that for most people exercise is likely to lead to only modest weight loss. This may be due to an insufficient amount of physical activity being performed together with compensatory changes in eating and exercise behaviours. This is hard to prove because energy intake and energy expenditure are difficult to quantify in free-living situations. Individual differences in the way people respond to exercise due to both environmental (e.g. social class, education level, income, eating and exercise behaviours of family and peers, weather etc.) and genetic factors also contribute to uncertainty about the effectiveness of physical activity for weight control. Nevertheless, physical activity remains a vital component of a healthy lifestyle due to its positive influence on energy balance as well as its potential to reduce the risk of lifestyle-related diseases

Acute exercise increases feeding latency in healthy normal weight young males but does not alter energy intake

This study investigated the acute influence of exercise on eating behaviour in an ecologically valid setting whereby healthy active males were permitted complete ad libitum access to food. Ten healthy males completed two, 8 h trials (exercise and control) in a randomised-crossover design. In the exercise trials participants consumed a breakfast snack and then rested for 1 h before undertaking a 60 min run (72% of V˙O2 max) on a treadmill. Participants then rested in the laboratory for 6 h during which time they were permitted complete ad libitum access to a buffet meal. The timing of meals, energy/macronutrient intake and eating frequency were assessed. Identical procedures were completed in the control trial except no exercise was performed. Exercise increased the length of time (35 min) before participants voluntarily requested to eat afterwards. Despite this, energy intake at the first meal consumed, or at subsequent eating episodes, was not influenced by exercise (total trial energy intake: control 7426 kJ, exercise 7418 kJ). Neither was there any difference in macronutrient intake or meal frequency between trials. These results confirm that food intake remains unaffected by exercise in the immediate hours after but suggest that exercise may invoke a delay before food is desired

Influence of prolonged treadmill running on appetite, energy intake and circulating concentrations of acylated ghrelin

The effects of prolonged treadmill running on appetite, energy intake and acylated ghrelin (an appetite stimulating hormone) were examined in 9 healthy males over the course of 24 h. Participants completed 2 experimental trials (exercise and control) in a randomised - crossover fashion. In the exercise trial participants ran for 90 min at 68.8 ± 0.8% of maximum oxygen uptake followed by 8.5 h of rest. Participants returned to the laboratory on the following morning to provide a fasting blood sample and ratings of appetite (24 h measurement). No exercise was performed on the control trial. Appetite was measured within the laboratory using visual analogue scales and energy intake was assessed from ad libitum buffet meals. Acylated ghrelin was determined from plasma using an ELISA assay. Exercise transiently suppressed appetite and acylated ghrelin but each remained no different from control values in the hours afterwards. Furthermore, despite participants expending 5324 kJ during exercise there was no compensatory increase in energy intake (24 h energy intake; control 17191 kJ, exercise 17606 kJ). These findings suggest that large energy deficits induced by exercise do not lead to acute compensatory responses in appetite, energy intake or acylated ghrelin

Influence of brisk walking on appetite, energy intake, and plasma acylated ghrelin

Purpose: This study examined the effect of an acute bout of brisk walking on appetite, energy intake, and the appetite-stimulating hormone-acylated ghrelin. Methods: Fourteen healthy young males (age 21.9 +/- 0.5 yr, body mass index 23.4 +/- 0.6 kg.m(-2), (V) over dotO(2max) 55.9 +/- 1.8 mL.kg(-1).min(-1); mean +/- SEM) completed two 8-h trials (brisk walking and control) in a randomized counterbalanced fashion. The brisk walking trial commenced with 60 min of subjectively paced brisk walking on a level-motorized treadmill after which participants rested for 7 h. Participants rested for the duration of the control trial. Ad libitum buffet meals were offered twice during main trials (1.5-2 and 5-5.5 h). Appetite (hunger, fullness, satisfaction, and prospective food consumption) was assessed at 30-min intervals throughout. Levels of acylated ghrelin, glucose, insulin, and triacylglycerol were determined from plasma. Results: Sixty minutes of brisk walking (7.0 +/- 0.1 km.h(-1)) yielded a net (exercise minus resting) energy expenditure of 2008 +/- 134 kJ, yet it did not significantly influence appetite, energy/macronutrient intake, or the plasma concentration of acylated ghrelin either during or after exercise (P > 0.05). Participants did not compensate for energy expended during walking, therefore a deficit in energy was induced (1836 kJ, 439 kcal) relative to control. Conclusions: This study demonstrates that, despite inducing a moderate energy deficit, an acute bout of subjectively paced brisk walking does not elicit compensatory responses in acylated ghrelin, appetite, or energy intake. This finding lends support for a role of brisk walking in weight management

The effect of exercise intensity on circulating hepatokine concentrations in healthy men [Abstract]

The effect of exercise intensity on circulating hepatokine concentrations in healthy men [Abstract

The impact of high intensity intermittent exercise on resting metabolic rate in healthy males

Introduction High-intensity intermittent exercise training (HIT) may favourably alter body composition despite low training volumes and predicted energy expenditure (EE). Purpose To characterise the acute impact of two common HIT protocols on EE and post-exercise oxygen consumption (11 h EPOC). Methods Oxygen consumption (l min−1), respiratory exchange ratio (RER) and EE were measured in nine healthy, lean males over 12 h under three conditions: control (CON), HIT1 (10 × 1 min high-intensity cycling bouts followed by 1 min rest) and HIT2 (10 × 4 min high-intensity cycling bouts followed by 2 min rest). Results Total exercise period EE during HIT1 (1,151 ± 205 kJ) (mean ± SD) was significantly lower than HIT2 (2,788 ± 322 kJ; p < 0.001). EE within the 60 min after exercise was significantly albeit marginally higher after HIT1 (388 ± 44 kJ; p = 0.02) and HIT2 (389 ± 39 kJ; p = 0.01) compared with CON (329 ± 39 kJ), with no difference between exercise conditions (p = 0.778). RER during this period was significantly lower in HIT1 (0.78 ± 0.06; p = 0.011) and HIT2 (0.76 ± 0.04; p = 0.004) compared with CON (0.87 ± 0.06). During the ‘slow phase’ of EPOC (1.25–9.75 h), there were no significant differences in EE (p = 0.07) or RER (p = 0.173) between trials

An evaluation of low volume high-intensity intermittent training (HIIT) for health risk reduction in overweight and obese men

Both sprint interval training (SIT) and high-intensity intermittent training (HIIT) have been described as time-efficient strategies for inducing favourable metabolic and cardiorespiratory adaptations in healthy and diseased participants. BACKGROUND: To date, little attention has been given to profiling the potential health benefits of HIIT or modified HIIT training within overweight and obese cohorts with particular focus on inflammation. Within this pilot trial, we tested the hypothesis that 6 sessions of HIIT performed over 2 weeks with 1-2 days’rest would improve aerobic capacity, glucose metabolism and inflammatory profile in an overweight and obese male cohort. Additionally, we profiled the potential health benefits of 4 HIIT sessions performed over the same period. METHODS: 18 overweight or obese males (BMI = 31.2 ± 3.6; V̇O2 = 30.3 ± 4.4 ml.kg.min-1) were studied before and 72 h after HIIT. Training sessions consisted of 10 x 1 min intervals at 90% HRpeak separated by 1 min recovery periods. Exercise was performed either 6 (group 1, n = 8) or 4 (group 2, n = 10)times over a 2 week period. RESULTS: After training no changes were detected from baseline for body composition, aerobic capacity, glucose metabolism or inflammatory profile(p > 0.05) in either group. CONCLUSION: Both 6 and 4 sessions of HIIT performed over a 2-week period are ineffective in improving selected health markers within an overweight and obese cohort

Exercise and ghrelin. A narrative overview of research

Since its discovery in 1999, ghrelin has been implicated in a multiplicity of physiological activities. Most notably, ghrelin has an important influence on energy metabolism and after the identification of its potent appetite stimulating effects ghrelin has been termed the ‘hunger hormone.’ Exercise is a stimulus which has a significant impact on energy homeostasis and consequently a substantial body of research has investigated the interaction between exercise and ghrelin. This narrative review provides an overview of research relating to the acute and chronic effects of exercise on circulating ghrelin (acylated, unacylated and total). To enhance study comparability, the scope of this review is limited to research undertaken in adult humans and consequently studies involving children and animals are not discussed. Although there is significant ambiguity within much of the early research, our review suggests that acute exercise transiently interferes with the production of acylated ghrelin. Furthermore, the consensus of evidence indicates that exercise training does not influence circulating ghrelin independent of weight loss. Additional research is needed to verify and extend the available literature, particularly by uncovering the mechanisms governing acute exercise-related changes and characterising responses in other populations such as females, older adults, and the obese

Influence of prior walking on postprandial lipaemia in South Asian and White European women

Influence of prior walking on postprandial lipaemia in South Asian and White European wome