Cardiovascular, muscular, and skeletal adaptations to recreational team handball training: a randomized controlled trial with young adult untrained men.

PURPOSE: The prevalence of lifestyle diseases has escalated, and effective exercise training programmes are warranted. This study tested the hypothesis that regular participation in small-sided team handball training could provide beneficial health effects on cardiovascular, skeletal, and muscular parameters in young adult untrained men. METHOD: Twenty-six untrained 20-30-year-old men were randomly allocated to either a team handball training group (HG; n = 14), which completed 1.9 ± 0.3 training sessions per week over 12 weeks, or an inactive control group (CG; n = 12). Physiological training adaptations were assessed pre- and post interventions by DXA scans, blood samples, muscle biopsies, and physical tests. RESULTS: The average heart rate during training was equivalent to 84 ± 4% of maximal heart rate. Compared to CG, HG displayed significant increases in VO2max (11 ± 6%), proximal femur bone mineral density (2 ± 1%), whole-body bone mineral content (2 ± 1%), intermittent endurance performance (32 ± 16%), incremental treadmill test performance (16 ± 7%) and muscle citrate synthase activity (22 ± 28%) as well as decreases in total fat mass (7 ± 7%) and total fat percentage (6 ± 7%) (all p < 0.05). There were no significant changes in muscle mass, blood pressure, resting heart rate, muscle hydroxyl-acyl-dehydrogenase activity, or blood lipids (all p > 0.05). CONCLUSION: Participation in regular recreational team handball training was associated with positive cardiovascular, skeletal, and muscular adaptations, including increased maximal oxygen uptake, increased muscle enzymatic activity, and improved bone mineralization as well as lower fat percentage. These findings suggest that recreational team handball training may be an effective health-promoting activity for young adult men.

Correction to: Cardiovascular, muscular, and skeletal adaptations to recreational team handball training: a randomized controlled trial with young adult untrained men.

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Effects of nitrate supplementation in trained and untrained muscle are modest with initial high plasma nitrite levels.

Nitrate (NO3-) supplementation resulting in higher plasma nitrite (NO2-) is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO2 ) during submaximal exercise in non-athletic populations, whereas effects in general are absent in endurance-trained individuals. To test whether physiologic effects of NO3- supplementation depend on local muscular training status or cardiovascular fitness, male endurance-trained cyclists (CYC, n=9, VO2 -max: 64±3 mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3 mL/min/kg), acutely consumed nitrate-rich beetroot juice ([NO3-] ~9 mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO2 -max) and incremental leg cycling (LEG-ex) and arm-cranking exercise (ARM-ex). NIT increased (P<.001) resting plasma NO3- by ~1200% relative to PLA. Plasma NO2- increased ~25% (P<.01) with a significant change only in CYC. LEG-ex VO2 (~2.60 L/min), ARM-ex VO2 (~1.14 L/min), and resting MAP (~87 mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG-ex VO2 (~2.03 L/min), ARM-ex VO2 (~1.06 L/min), or resting MAP (~85 mm Hg). VO2 -max was not affected by supplementation, but incremental test peak power was higher (P<.05) in LEG-ex for CYC in NIT relative to PLA (418±47 vs 407±46 W). In both CYC and CON, high initial baseline values and small increases in plasma NO2- after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of NO3- supplementation.

Plantar flexor neuromuscular adjustments following match-play football in hot and cool conditions.

We assessed neuromuscular fatigue and recovery of the plantar flexors after playing football with or without severe heat stress. Neuromuscular characteristics of the plantar flexors were assessed in 17 male players at baseline and ∼30 min, 24, and 48 h after two 90-min football matches in temperate (∼20 °C and 55% rH) and hot (∼43 °C and 20% rH) environments. Measurements included maximal voluntary strength, muscle activation, twitch contractile properties, and rate of torque development and soleus EMG (i.e., root mean square activity) rise from 0 to 30, -50, -100, and -200 ms during maximal isometric contractions for plantar flexors. Voluntary activation and peak twitch torque were equally reduced (-1.5% and -16.5%, respectively; P < 0.05) post-matches relative to baseline in both conditions, the latter persisting for at least 48 h, whereas strength losses (∼5%) were not significant. Absolute explosive force production declined (P < 0.05) 30 ms after contraction onset independently of condition, with no change at any other epochs. Globally, normalized rate of force development and soleus EMG activity rise values remained unchanged. In football, match-induced alterations in maximal and rapid torque production capacities of the plantar flexors are moderate and do not differ after competing in temperate and hot environments.

Time course of natural heat acclimatization in well-trained cyclists during a 2-week training camp in the heat.

The aim of this study was to determine the time course of physiological adaptations and their relationship with performance improvements during 2 weeks of heat acclimatization. Nine trained cyclists completed 2 weeks of training in naturally hot environment (34 ± 3 °C; 18 ± 5% relative humidity). On days 1, 6, and 13, they performed standardized heat response tests (HRT-1, 2, 3), and 43.4-km time trials in the heat (TTH-1, 2, 3) were completed on days 2, 7, and 14. Within the first 5-6 days, sweat sodium concentration decreased from 75 ± 22 mmol/L to 52 ± 24 mmol/L, sweat rate increased (+20 ± 15%), and resting hematocrit decreased (-5.6 ± 5.4%), with no further changes during the remaining period. In contrast, power output during TTHs gradually improved from TTH-1 to TTH-2 (+11 ± 8%), and from TTH-2 to TTH-3 (+5 ± 4%). Individual improvements in performance from TTH-1 to TTH-2 correlated with individual changes in hematocrit (assessed after the corresponding HRT; r = -0.79, P < 0.05), however, were not related to changes in performance from TTH-2 to TTH-3. In trained athletes, sudomotor and hematological adaptations occurred within 5-6 days of training, whereas the additional improvement in performance after the entire acclimatization period did not relate to changes in these parameters.

Heat acclimatization does not improve VO2max or cycling performance in a cool climate in trained cyclists.

This study investigated if well-trained cyclists improve V ˙ O 2 m a x and performance in cool conditions following heat acclimatization through natural outdoor training in hot conditions. Eighteen trained male cyclists were tested for physiological adaptations, V ˙ O 2 m a x , peak aerobic power output, exercise efficiency, and outdoor time trial (TT) performance (43.4 km in cool environment, ∼5-13 °C) before and after 2 weeks of training in a cool (CON, n = 9) or hot (∼35 °C, HA, n = 9) environment. After heat acclimatization, TT performance in the heat was improved by 16%; however, there was no change in the HA group in V ˙ O 2 m a x (4.79 ± 0.21 L/min vs 4.82 ± 0.35 L/min), peak aerobic power output (417 ± 16 W vs 422 ± 17 W), and outdoor TT performance in cool conditions (300 ± 14 W/69 ± 3 min vs 302 ± 9 W/69 ± 4 min). The present study shows that 2 weeks of heat acclimatization was associated with marked improvements in TT performance in the heat. However, for the well-trained endurance athletes, this did not transfer to an improved aerobic exercise capacity or outdoor TT performance in cool conditions.

Consensus recommendations on training and competing in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat.

Consensus recommendations on training and competing in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimise performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimise performance is to heat acclimatise. Heat acclimatisation should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimise dehydration during exercise. Following the development of commercial cooling systems (eg, cooling-vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organisers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimising the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events, for hydration and body cooling opportunities, when competitions are held in the heat.

Pro- and anti-angiogenic factors in human skeletal muscle in response to acute exercise and training.

This study examined the effect of acute exercise and 4 weeks of aerobic training on skeletal muscle gene and protein expression of pro- and anti-angiogenic factors in 14 young male subjects. Training consisted of 60 min of cycling (∼60% of ), 3 times/week. Biopsies were obtained from vastus lateralis muscle before and after training. Muscle interstitial fluid was collected during cycling at weeks 0 and 4. Training increased (P < 0.05) the capillary: fibre ratio and capillary density by 23% and 12%, respectively. The concentration of interstitial vascular endothelial growth factor (VEGF) in response to acute exercise increased similarly (>6-fold; P < 0.05) before and after training. Resting protein levels of soluble VEGF receptor-1 in interstitial fluid, and of VEGF, thrombospondin-1 (TSP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP1) in muscle were unaffected by training, whereas endothelial nitric oxide synthase protein levels in muscle increased by 50% (P < 0.05). Before and after training, acute exercise induced a similar increase (P < 0.05) in the mRNA level of angiopoietin 2, matrix metalloproteinase 9 and TSP-1. After training, TIMP1 mRNA content increased with exercise (P < 0.05). In conclusion, acute exercise induced a similar increase in the gene-expression of both pro- and anti-angiogenic factors in untrained and trained muscle. We propose that the increase in anti-angiogenic factors with exercise is important for modulation of angiogenesis. The lack of effect of training on basal muscle VEGF protein levels and VEGF secretion during exercise suggests that increased VEGF levels are not a prerequisite for exercise-induced capillary growth in healthy muscle.

Physiological and performance adaptations to an in-season soccer camp in the heat: associations with heart rate and heart rate variability.

The aim of the present study was to examine the associations between adaptive responses to an in-season soccer training camp in the heat and changes in submaximal exercising heart rate (HRex, 5-min run at 9 km/h), postexercise HR recovery (HRR) and HR variability (HRV). Fifteen well-trained but non-heat-acclimatized male adult players performed a training week in Qatar (34.6 ± 1.9°C wet bulb globe temperature). HRex, HRR, HRV (i.e. the standard deviation of instantaneous beat-to-beat R-R interval variability measured from Poincaré plots SD1, a vagal-related index), creatine kinase (CK) activity, plasma volume (PV) changes, and post-5-min run rate of perceived exertion (RPE) were collected at six occasions in temperate environmental conditions (22°C). Players also performed the yo-yo intermittent recovery test level 1 (Yo-Yo IR1) in the same environmental conditions (22°C), both at the beginning and at the end of the training week. Throughout the intervention, HRex and HRV showed decreasing (P < 0.001) and increasing (P < 0.001) trends, respectively, while HRR remained unaffected (P = 0.84). Changes in HRex [-0.52, 90% confidence limits (-0.64; -0.38), P < 0.001] and SD1 [0.35 (0.19; 0.49), P < 0.001] were correlated with those in PV. There was no change in RPE (P = 0.92), while CK varied according to training contents (P < 0.001), without association with HR-derived measures. Yo-Yo IR1 performance increased by 7 ± 9% (P = 0.009), which was correlated with changes in HRex [-0.64 (-0.84; -0.28), P = 0.01]. In conclusion, we found that an in-season soccer training camp in the heat can significantly improve PV and soccer-specific physical performance; both of which are associated with changes in HRex during a 5-min submaximal run.

ClimApp-Integrating Personal Factors with Weather Forecasts for Individualised Warning and Guidance on Thermal Stress.

This paper describes the functional development of the ClimApp tool (available for free on iOS and Android devices), which combines current and 24 h weather forecasting with individual information to offer personalised guidance related to thermal exposure. Heat and cold stress assessments are based on ISO standards and thermal models where environmental settings and personal factors are integrated into the ClimApp index ranging from -4 (extremely cold) to +4 (extremely hot), while a range of -1 and +1 signifies low thermal stress. Advice for individuals or for groups is available, and the user can customise the model input according to their personal situation, including activity level, clothing, body characteristics, heat acclimatisation, indoor or outdoor situation, and geographical location. ClimApp output consists of a weather summary, a brief assessment of the thermal situation, and a thermal stress warning. Advice is provided via infographics and text depending on the user profile. ClimApp is available in 10 languages: English, Danish, Dutch, Swedish, Norwegian, Hellenic (Greek), Italian, German, Spanish and French. The tool also includes a research functionality providing a platform for worker and citizen science projects to collect individual data on physical thermal strain and the experienced thermal strain. The application may therefore improve the translation of heat and cold risk assessments and guidance for subpopulations. ClimApp provides the framework for personalising and downscaling weather reports, alerts and advice at the personal level, based on GPS location and adjustable input of individual factors.

Cycling in the heat: performance perspectives and cerebral challenges.

Cycling performances require periods with high power output and consequently large endogenous heat production. During cycling in temperate or cold climates, heat is mainly released from the skin to the surroundings via convection, whereas evaporative heat loss becomes the dominant or only mechanism for heat dissipation when the environmental temperature increases. Accordingly, large sweat rates are required, which may challenge the cyclists' electrolyte and water balance. Furthermore, the cooling capacity of the environment may become a limiting factor for the ability to maintain heat balance, for example during cycling in very humid climates or when cycling up-hill as the wind speed decreases and reduces the maximal rate of evaporative heat loss. Hyperthermia may in itself hamper performance, but especially in combination with dehydration it may deteriorate the cyclist's ability to maintain power output. Fatigue mechanisms involve cardiovascular stressing, but it also appears that factors within the central nervous system are of major importance for motor performance during such exercise. However, the influence of the environmental temperature on cycling performance appears to vary markedly depending on the course, the air humidity and the cyclist ability to avoid dehydration. If hyperthermia becomes a major issue, it will deteriorate performance, but as long as temperature and water balance can be established, the high air temperature may actually benefit performance because air density and air resistance will decrease and lower the power output required to maintain a given velocity.

Recreational football as a health promoting activity: a topical review.

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.

Performance enhancements and muscular adaptations of a 16-week recreational football intervention for untrained women.

The present study investigated the performance effects and physiological adaptations over 16 weeks of recreational football training and continuous running for healthy untrained premenopausal women in comparison with an inactive control group [Football group (FG): n=21; running group (RG): n=18; CO: n=14]. Two weekly 1-h training sessions were performed in FG and RG. After 4 and 16 weeks of training VO(2max) was elevated (P<0.05) by 7% and 15%, respectively, in FG, and by 6% and 10%, respectively, in RG. After 16 weeks, Yo-Yo intermittent endurance level 2 performance was 33% and 19% better (P<0.05) for FG and 29% and 21% better (P<0.05) for RG than after 4 and 0 weeks, respectively. Peak sprinting speed was 12% higher (21.0 +/- 0.6 vs 18.8 +/- 0.7 km/h; P<0.05) for FG after the training period, whereas no difference was observed for RG. After 4 weeks citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD) activity was 9% and 8%, respectively, higher (P<0.05) than before training in FG with no further changes during the last 12 weeks. In RG, CS increased (P<0.05) by 12% after 4 weeks and no significant increase was observed for HAD. In FG, the number of capillaries per fiber was 18% higher (P<0.05) after 16 weeks (2.44 +/- 0.15 vs 2.07 +/- 0.05 cap/fiber), with no significant difference for RG. No differences were observed between 0 and 16 weeks for CO. In conclusion, recreational women's football leads to significant increases in VO(2max), performance and muscular adaptations throughout a 16-week training period. Thus, football can be used as an activity to elevate the physical capacity of untrained women.

Activity profile and physiological response to football training for untrained males and females, elderly and youngsters: influence of the number of players.

The present study examined the activity profile, heart rate and metabolic response of small-sided football games for untrained males (UM, n=26) and females (UF, n=21) and investigated the influence of the number of players (UM: 1v1, 3v3, 7v7; UF: 2v2, 4v4 and 7v7). Moreover, heart rate response to small-sided games was studied for children aged 9 and 12 years (C9+C12, n=75), as well as homeless (HM, n=15), middle-aged (MM, n=9) and elderly (EM, n=11) men. During 7v7, muscle glycogen decreased more for UM than UF (28 +/- 6 vs 11 +/- 5%; P<0.05) and lactate increased more (18.4 +/- 3.6 vs 10.8 +/- 2.1 mmol kg(-1) d.w.; P<0.05). For UM, glycogen decreased in all fiber types and blood lactate, glucose and plasma FFA was elevated (P<0.05). The mean heart rate (HR(mean)) and time >90% of HR(max) ranged from 147 +/- 4 (EM) to 162 +/- 2 (UM) b.p.m. and 10.8 +/- 1.5 (UF) to 47.8 +/- 5.8% (EM). Time >90% of HR(max) (UM: 16-17%; UF: 8-13%) and time spent with high speed running (4.1-5.1%) was similar for training with 2-14 players, but more high-intensity runs were performed with few players (UM 1v1: 140 +/- 17; UM 7v7: 97 +/- 5; P<0.05): Small-sided games were shown to elucidate high heart rates for all player groups, independently of age, sex, social background and number of players, and a high number of intense actions both for men and women. Thus, small-sided football games appear to have the potential to create physiological adaptations and improve performance with regular training for a variety of study groups.

Positive performance and health effects of a football training program over 12 weeks can be maintained over a 1-year period with reduced training frequency.

We examined whether improvements in the performance and health profile of an intensive 12-week football intervention could be maintained with a reduced training frequency. Seventeen healthy untrained males completed the study. Ten subjects trained 2.4 times/week for 12 weeks and another 52 weeks with 1.3 sessions/week [football group (FG)] and seven subjects acted as controls [control group (CG)]. For FG, fat mass (3.2 kg) and systolic blood pressure (8 mmHg) were lower (P<0.05) after 64 than 0 weeks, and VO(2max) (8%) and Yo-Yo intermittent endurance level 2 test performance (49%) were higher (P<0.05), with no difference between 64 and 12 weeks. After 64 weeks, quadriceps muscle mass (11%), mean fiber area (10%) and citrate synthase activity (18%) were higher (P<0.05) than those at 0 weeks. Leg bone mass (3.5%) and density (2.0%) were higher (P<0.05) after 64 than 0 weeks, but not different between 12 and 0 weeks. Plantar jump force (17-18%), 30-m sprinting velocity (1.3-3.0%) and muscle glycogen concentration (19-21%) were higher (P<0.05) and blood lactate during submaximal exercise was lower (27-72%, P<0.05) after 64 than after 12 and 0 weeks. The above-mentioned variables were unaltered for CG. In conclusion, positive adaptations in cardiovascular fitness obtained over 12 weeks of regular recreational football training can be maintained over a 1-year period with a reduced training frequency, with further development in musculo-skeletal fitness.

Beneficial effects of recreational football on the cardiovascular risk profile in untrained premenopausal women.

The present study examined the cardiovascular health effects of 16 weeks of recreational football training in untrained premenopausal women in comparison with continuous running training. Fifty healthy women were matched and randomized to a football (FG, n=25) or a running (RG, n=25) group and compared with a control group with no physical training (CO, n=15). Training was performed for 1 h twice a week. After 16 weeks, systolic and diastolic blood pressure was reduced (P<0.05) in FG (7+/-2 and 4+/-1 mmHg) and systolic blood pressure was lowered (P<0.05) in RG (6+/-2 mmHg). After 16 weeks, resting heart rate was lowered (P<0.05) by 5+/-1 bpm both in FG and RG, and maximal oxygen uptake was elevated (P<0.05) by 15% in FG and by 10% in RG (5.0+/-0.7 and 3.6+/-0.6 mL/min/kg, respectively). Total fat mass decreased (P<0.05) by 1.4+/-0.3 kg in FG and by 1.1+/-0.3 kg in RG. After 16 weeks, pulse pressure wave augmentation index (-0.9+/-2.5 vs 4.2+/-2.4%), skeletal muscle capillarization (2.44+/-0.15 vs 2.07+/-0.05 cap/fib) and low-density lipoprotein/high-density lipoprotein cholesterol ratio were improved (P<0.05) in FG, but not altered in RG. No changes were observed in CO. In conclusion, regular recreational football training has significant favorable effects on the cardiovascular risk profile in untrained premenopausal women and is at the least as efficient as continuous running.

Recreational soccer is an effective health-promoting activity for untrained men.

To examine the effects of regular participation in recreational soccer on health profile, 36 healthy untrained Danish men aged 20-43 years were randomised into a soccer group (SO; n = 13), a running group (RU; n = 12) and a control group (CO; n = 11). Training was performed for 1 h two or three times per week for 12 weeks; at an average heart rate of 82% (SEM 2%) and 82% (1%) of HR(max) for SO and RU, respectively. During the 12 week period, maximal oxygen uptake increased (p<0.05) by 13% (3%) and 8% (3%) in SO and RU, respectively. In SO, systolic and diastolic blood pressure were reduced (p<0.05) from 130 (2) to 122 (2) mm Hg and from 77 (2) to 72 (2) mm Hg, respectively, after 12 weeks, with similar decreases observed for RU. After the 12 weeks of training, fat mass was 3.0% (2.7 (0.6) kg) and 1.8% (1.8 (0.4) kg) lower (p<0.05) for SO and RU, respectively. Only SO had an increase in lean body mass (1.7 (0.4) kg, p<0.05), an increase in lower extremity bone mass (41 (8) g, p<0.05), a decrease in LDL-cholesterol (2.7 (0.2) to 2.3 (0.2) mmol/l; p<0.05) and an increase (p<0.05) in fat oxidation during running at 9.5 km/h. The number of capillaries per muscle fibre was 23% (4%) and 16% (7%) higher (p<0.05) in SO and RU, respectively, after 12 weeks. No changes in any of the measured variables were observed for CO. In conclusion, participation in regular recreational soccer training, organised as small-sided drills, has significant beneficial effects on health profile and physical capacity for untrained men, and in some aspects it is superior to frequent moderate-intensity running.