INT for 12 wk is an effective training stimulus for improvement of cardiorespiratory fitness and glucose tolerance, but in relation to the treatment of hyperlipidemia and obesity, it is less effective than prolonged training. Furthermore and in contrast to strength training, 12 wk of INT had no impact on muscle mass or indices of skeletal health.

The present review addresses the physiological demands during recreational football training and the effects on central health variables that influence the risk of life-style diseases of young and middle-aged men. Recent studies have established that recreational football, carried out as small-sided games can be characterized as having a high aerobic component with mean heart rates of 80-85% of maximum heart rate, which is similar to values observed for elite football players. In addition, the training includes multiple high-speed runs, sprints, turns, jumps and tackles, which provide a high impact on muscles and bones. Recreational football training in untrained men results in marked improvements in maximum aerobic power, blood pressure, muscle capillarization and intermittent exercise performance, and those effects are similar to interval training and more pronounced than moderate-intensity continuous running and strength training. Further, recreational football training enhances fat oxidation during exercise and results in a higher fat loss than interval training and strength training, and results in marked muscle hypertrophy and elevates bone mass, more than interval and continuous running. Taken together, recreational football appears to effectively stimulate musculoskeletal, metabolic and cardiovascular adaptations of importance for health and thereby reduces the risk of developing life-style diseases.

This study examined the effect of two different intense exercise training regimens on skeletal muscle ion transport systems, performance, and metabolic response to exercise. Thirteen subjects performed either sprint training [ST; 6-s sprints (n = 6)], or speed endurance training [SET; 30-s runs approximately 130% Vo(2 max), n = 7]. Training in the SET group provoked higher (P < 0.05) plasma K(+) levels and muscle lactate/H(+) accumulation. Only in the SET group was the amount of the Na(+)/H(+) exchanger isoform 1 (31%) and Na(+)-K(+)-ATPase isoform alpha(2) (68%) elevated (P < 0.05) after training. Both groups had higher (P < 0.05) levels of Na(+)-K(+)-ATPase beta(1)-isoform and monocarboxylate transporter 1 (MCT1), but no change in MCT4 and Na(+)-K(+)-ATPase alpha(1)-isoform. Both groups had greater (P < 0.05) accumulation of lactate during exhaustive exercise and higher (P < 0.05) rates of muscle lactate decrease after exercise. The ST group improved (P < 0.05) sprint performance, whereas the SET group elevated (P < 0.05) performance during exhaustive continuous treadmill running. Improvement in the Yo-Yo intermittent recovery test was larger (P < 0.05) in the SET than ST group (29% vs. 10%). Only the SET group had a decrease (P < 0.05) in fatigue index during a repeated sprint test. In conclusion, turnover of lactate/H(+) and K(+) in muscle during exercise does affect the adaptations of some but not all related muscle ion transport proteins with training. Adaptations with training do have an effect on the metabolic response to exercise and specific improvement in work capacity.

Key pointsr The power-asymptote (critical power; CP) of the hyperbolic power-time relationship for high-intensity exercise defines a threshold between steady-state and non-steady-state exercise intensities and the curvature constant (W ) indicates a fixed capacity for work >CP that is related to a loss of muscular efficiency.r The present study reports novel evidence on the muscle metabolic underpinnings of CP and W during whole-body exercise and their relationships to muscle fibre type.r We show that the W is not correlated with muscle fibre type distribution and that it represents an elevated energy contribution from both oxidative and glycolytic/glycogenolytic metabolism.r We show that there is a positive correlation between CP and highly oxidative type I muscle fibres and that muscle metabolic steady-state is attainable CP.r Our findings indicate a mechanistic link between the bioenergetic characteristics of muscle fibre types and the power-time relationship for high-intensity exercise.Abstract We hypothesized that: (1) the critical power (CP) will represent a boundary separating steady-state from non-steady-state muscle metabolic responses during whole-body exercise and (2) that the CP and the curvature constant (W ) of the power-time relationship for high-intensity exercise will be correlated with type I and type IIx muscle fibre distributions, respectively. Four men and four women performed a 3 min all-out cycling test for the estimation of CP and constant work rate (CWR) tests slightly >CP until exhaustion (T lim ), slightly CP T lim isotime to test the first hypothesis. Eleven men performed 3 min all-out tests and donated muscle biopsies to test the second hypothesis. Below CP, muscle [PCr] [42.6 ± 7.1 vs. 49.4 ± 6.9 mmol (kg d.w.) −1 ], [La − ] [34.8 ± 12.6 vs. 35.5 ± 13.2 mmol (kg d.w.) −1 ] and pH (7.11 ± 0.08 vs. 7.10 ± 0.11) remained stable between ß12 and 24 min (P > 0.05 for all), whereas these variables changed with time >CP such that they were greater [[La − ] 95.6 ± 14.1 mmol (kg d.w.) −1 ] and lower [[PCr] 24.2 ± 3.9 mmol (kg d.w.) −1 ; pH 6.84 ± 0.06] (P < 0.05) at T lim (740 ± 186 s) than during the

Interstitial K+ ([K+]i) was measured in human skeletal muscle by microdialysis during exhaustive leg exercise, with (AL) and without (L) previous intense arm exercise. In addition, the reproducibility of the [K+]i determinations was examined. Possible microdialysis-induced rupture of the sarcolemma was assessed by measurement of carnosine in the dialysate, because carnosine is only expected to be found intracellularly. Changes in [K+]i could be reproduced, when exhaustive leg exercise was performed on two different days, with a between-day difference of ∼0.5 mM at rest and 1.5 mM at exhaustion. The time to exhaustion was shorter in AL than in L (2.7 ± 0.3 vs. 4.0 ± 0.3 min; P < 0.05). Furthermore, [K+]i was higher from 0 to 1.5 min of the intense leg exercise period in AL compared with L (9.2 ± 0.7 vs. 6.4 ± 0.9 mM; P < 0.001) and at exhaustion (11.9 ± 0.5 vs. 10.3 ± 0.6 mM; P < 0.05). The dialysate content of carnosine was elevated by exercise, but low-intensity exercise resulted in higher dialysate carnosine concentrations than subsequent intense exercise. Furthermore, no relationship was found between carnosine concentrations and [K+]i. Thus the present data suggest that microdialysis can be used to determine muscle [K+]i kinetics during intense exercise, when low-intensity exercise is performed before the intense exercise. The high [K+]i levels reached at exhaustion can be expected to cause fatigue, which is supported by the finding that a faster accumulation of interstitial K+, induced by prior arm exercise, was associated with a reduced time to fatigue.

The present study examined the effects of short-term recreational football training on blood pressure (BP), fat mass, and fitness in sedentary, 35-50-year-old premenopausal women with mild hypertension. Forty-one untrained, hypertensive women were randomized into a football training group (n = 21; FTG) and a control group (n = 20; CON). FTG performed 45 ± 1 1-h small-sided football training sessions during the 15-week intervention period. BP, body composition (dual-energy x-ray absorptiometry), blood lipid profile, and fitness level were determined pre-and post-intervention. After 15 weeks, systolic and diastolic BP, respectively, were lowered more (P < 0.05) in FTG (−12 ± 3 and −6 ± 2 mmHg) than in CON (−1 ± 1 and 1 ± 2 mmHg). Total body fat mass

background A previous meta-analysis showed that maximal oxygen uptake increased by 3.51 mL/ kg/min (95% CI 3.07 to 4.15) during a recreational football programme of 3-6 months in comparison with continuous moderate-intensity running, strength training or a passive control group. In addition, narrative reviews have demonstrated beneficial effects of recreational football on physical fitness and health status. Objective The purpose of this systematic review and meta-analysis was to evaluate the magnitude of effects of recreational football on blood pressure, body composition, lipid profile and muscular fitness with reference to age, gender and health status. Design Systematic review and meta-analysis. Data sources MEDLINE, PubMed, SPORTDiscus, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Google Scholar were searched prior to 1 February 2017. In addition, Google Scholar alerts were set up in January 2012 to identify potential papers with the following key terms: recreational football, recreational soccer, street football and street soccer. Eligibility criteria for selecting studies Randomised and matched controlled trials with participants allocated to a recreational football group or any other type of exercises or passive control group were included. Training programmes had to last at least 2 weeks to meet the inclusion criteria. The primary outcome measures were blood pressure, resting heart rate, body composition, muscular fitness, and blood lipids and glucose tolerance. A total of 31 papers met the inclusion criteria and were included. Results The effect of recreational football on systolic blood pressure (SBP) versus no-exercise controls was most likely extremely largely beneficial (effect size (ES)=4.20 mm Hg; 95% CI 1.87 to 6.53). In addition, a most likely very large beneficial (ES=3.89 mm Hg; 95% CI 2.33 to 5.44) effect was observed for diastolic blood pressure (DBP), when compared with non-active groups. Furthermore, a most likely extremely large beneficial effect was shown for SBP and DBP in participants with mild hypertension (11 and 7 mm Hg decrease, respectively) and participants with prehypertension (10 and 7 mm Hg decrease, respectively). Meta-analysis of recreational football determined the impact on resting heart rate as most likely extremely largely beneficial (ES=6.03 beats/min; 95% CI 4.43 to 7.64) when compared with non-active groups. The observed recreational football effect on fat mass was most likely largely beneficial (ES=1.72 kg; 95% CI 0.86 to 2.58) and the effect on countermovement jump (CMJ) performance was most likely very largely beneficial (ES=2.27 cm; 95% CI 1.29 to 3.25) when compared with non-active groups. Possibly beneficial decreases were found in low-density lipoprotein levels (ES=0.21 mmol/L; 95% CI 0.06 to 0.36). Possibly largely beneficial effect was observed for DBP in comparison with continuous running training. Small harmful and unclear results were noted for SBP, fat and lean body mass, body mass index, as well as muscu...

This study demonstrates that previous glycogen depletion of ST fibers enhances FT fiber recruitment, elevates O2 cost, and causes a slow component of VO2 during dynamic exercise with no blood lactate accumulation or muscular acidosis. These findings suggest that FT fiber recruitment elevates energy requirement of dynamic exercise in humans and support an important role of active FT fibers in producing the slow component of VO2