Peak fat oxidation, peak oxygen uptake, and running performance increase during pre-season in sub-elite male football players.

PURPOSE: In Football, the high-intensity running bouts during matches are considered decisive. Interestingly, recent studies showed that peak fat oxidation rates (PFO) are higher in football players than other athletes. This study aimed to investigate whether PFO increases following a pre-season. Secondarily, and due to COVID-19, we investigated whether PFO is related to the physical performance in a subgroup of semi-professional male football players. METHODS: Before and after 8 weeks of pre-season training, 42 sub-elite male football players (18 semi-professionals and 24 non-professionals) had a dual-energy x-ray absorptiometry scan and performed a graded exercise test on a treadmill for the determination of PFO, the exercise intensity eliciting PFO (Fatmax) and peak oxygen uptake (V̇O2peak). Additionally, the semi-professional players performed a Yo-Yo Intermittent Recovery Test level 2 (YYIR2) before and after pre-season training to determine football-specific running performance. RESULTS: PFO increased by 11 ± 10% (mean ± 95% CI), p = 0.031, and V̇O2peak increased by 5 ± 1%, p < 0.001, whereas Fatmax was unchanged (+12 ± 9%, p = 0.057), following pre-season training. PFO increments were not associated with increments in V̇O2peak (Pearson's r2 = 0.00, p = 0.948) or fat-free mass (FFM) (r2 = 0.00, p = 0.969). Concomitantly, YYIR2 performance increased in the semi-professional players by 39 ± 17%, p < 0.001, which was associated with changes in V̇O2peak (r2 = 0.35, p = 0.034) but not PFO (r2 = 0.13, p = 0.244). CONCLUSIONS: PFO, V̇O2peak, and FFM increased following pre-season training in sub-elite football players. However, in a subgroup of semi-professional players, increments in PFO were not associated with improvements in YYIR2 performance nor with increments in V̇O2peak and FFM.

The recovery of muscle function and glycogen levels following game-play in young elite male ice hockey players.

Despite the frequent occurrence of congested game fixtures in elite ice hockey, the postgame recovery pattern has not previously been investigated. The purpose of the present study was therefore to evaluate the acute decrements and subsequent recovery of skeletal muscle glycogen levels, muscle function and repeated-sprint ability following ice hockey game-play. Sixteen male players from the Danish U20 national team completed a training game with muscle biopsies obtained before, postgame and following ~38 h of recovery (day 2). On-ice repeated-sprint ability and muscle function (maximal voluntary isometric [MVIC] and electrically induced low- (20 Hz) and high-frequency (50 Hz) knee-extensor contractions) were assessed at the same time points, as well as ~20 h into recovery (day 1). Muscle glycogen decreased 31% (p < 0.001) postgame and had returned to pregame levels on day 2. MVIC dropped 11%, whereas 50 and 20 Hz torque dropped 21% and 29% postgame, respectively, inducing a 10% reduction in the 20/50 Hz torque ratio indicative of low-frequency force depression (all p < 0.001). While MVIC torque returned to baseline on day 1, 20 and 50 Hz torque remained depressed by 9%-11% (p = 0.010-0.040), hence restoring the pre-exercise 20/50 Hz ratio. Repeated-sprint ability was only marginally reduced by 1% postgame (p = 0.041) and fully recovered on day 1. In conclusion, an elite youth ice hockey game induces substantial reductions in muscle glycogen content and muscle function, but only minor reductions in repeated-sprint ability and with complete recovery of all parameters within 1-2 days postgame.

Physical performance and loading for six playing positions in elite female football: full-game, end-game, and peak periods.

The present study investigated the position-specific match demands and heart rate response of female elite footballers, with special focus on the full-game, end-game, and peak-intensity periods. In total, 217 match observations were performed in 94 players from all eight teams of the best Danish Women's League, that is, goalkeepers (GK, n = 10), central defenders (CD, n = 23), full-backs (FB, n = 18), central midfielders (CM, n = 28), external midfielders (EM, n = 18), and forwards (FW, n = 11). Positional data (GPS; 10 Hz Polar Team Pro) and HR responses were collected. HRmean and HRpeak were 87%-89% and 98%-99% of HRmax , for outfield players, with no positional differences. CM, EM, and FB covered 8%-14% greater (P < .001) match distances than CD. EM, FW, FB, and CM performed 40%-64% more (P < .05) high-speed running and 41%-95% more (P < .01) very-high-speed running (VHSR) than CD. From the first to the last 15-minute period, total distance, except for FW, number of VHSR, except FB, peak speed and sum of accelerations and sum of decelerations decreased (P < .05) for all outfield positions. In the most intense 5-minute period, EM, FB, and CM performed 25%-34% more (P < .01) HSR than CD, whereas EM, FW, and FB performed 36%-49% more (P < .01) VHSR than CD. In conclusion, competitive elite female matches impose high physical demands on all outfield playing positions, with high aerobic loading throughout matches and marked declines in high-speed running and intense accelerations and decelerations toward the end of games. Overall physical match demands are much lower for central defenders than for the other outfield playing positions, albeit this difference is minimized in peak-intensity periods.

Can psychological characteristics, football experience, and player status predict state anxiety before important matches in Danish elite-level female football players?

Elite football can make players feel nervous, and personality characteristics, as well as experience, affect how well pressure is handled before important games. Studying the psychological characteristics of female football players can provide information on how well psychological pressure is handled and generate knowledge on how to support players in order to improve performance. Based on a sample of 128 female elite football players from 8 top-level teams, the present study investigates whether psychological characteristics and football experience/player stus in elite female football players can predict state anxiety before important matches. Our results outline that high age and national team experience negatively predicted most of the trait anxiety subscales. In line with previous research, no psychological differences were found between goalkeepers, defenders, midfielders, and strikers while starting players revealed to have significantly lower trait anxiety. When measuring before important matches, we found that somatic state anxiety was negatively associated with senior national team experience and positively associated with worry trait anxiety and fear of failure. Cognitive state anxiety was negatively associated with hope for success and positively associated with somatic and worry trait anxiety. Self-confidence was positively associated with youth national team experience and negatively associated with worry trait anxiety. It can be concluded that psychological characteristics and national team experience are both important for optimal state anxiety before important matches in elite-level women's football. Implications for practice and future research are discussed.

Acute arm and leg muscle glycogen and metabolite responses to small-sided football games in healthy young men.

PURPOSE: Studies have indicated upper body involvement during football, provoking long-term muscular adaptations. This study aimed at examining the acute metabolic response in upper and lower body skeletal muscle to football training organized as small-sided games (SSG). METHODS: Ten healthy male recreational football players [age 24 ± 1 (± SD) yrs; height 183 ± 4 cm; body mass 83.1 ± 9.7 kg; body fat 15.5 ± 5.4%] completed 1-h 5v5 SSG (4 × 12 min interspersed with 4-min recovery periods). Muscle biopsies were obtained from m. vastus lateralis (VL) and m. deltoideus (DE) pre- and post-SSG for muscle glycogen and metabolite analyses. Blood lactate samples were obtained at rest, middle and end of the SSG. RESULTS: Muscle glycogen in VL decreased (P < 0.01) by 21% and tended (P = 0.08) to decrease in DE by 13%. Muscle lactate increased in VL (117%; P < 0.001) and DE (81%; P < 0.001) during the game, while blood lactate rose threefold. Muscle ATP and PCr were unaltered, but intermuscular differences were detected for ATP at both time points (P < 0.001) and for PCr at pre-SSG (P < 0.05) with VL demonstrating higher values than DE, while muscle creatine rose in VL (P < 0.001) by 41% and by 22% in DE (P = 0.02). Baseline citrate synthase maximal activity was higher (P < 0.05) in VL compared to DE, whereas baseline muscle lactate concentration was higher (P < 0.05) in DE than VL. CONCLUSION: The upper body may be extensively involved during football play, but besides a rise in muscle lactate in the deltoideus muscle similar to the leg muscles, the present study did not demonstrate acute metabolic changes of an order that may explain the previously reported training effect of football play in the upper extremities.

On-Ice and Off-Ice Fitness Profiles of Elite and U20 Male Ice Hockey Players of Two Different National Standards.

Vigh-Larsen, JF, Haverinen, MT, Panduro, J, Ermidis, G, Andersen, TB, Overgaard, K, Krustrup, P, Parkkari, J, Avela, J, Kyröläinen, H, and Mohr, M. On-ice and off-ice fitness profiles of elite and U20 male ice hockey players of two different national standards. J Strength Cond Res 34(12): 3369-3376, 2020-Differences in body composition and performance were investigated between elite and U20 male ice hockey players of 2 different national standards. One hundred seventy-nine players were recruited from the highest Finnish (n = 82) and Danish (n = 61) national level, as well as from 1 U20 team from Finland (n = 19) and Denmark (n = 17). Body composition and countermovement jump performance (CMJ) were measured off-ice in addition to on-ice assessments of agility, 10- and 30-m sprint performance, and endurance capacity (the maximal Yo-Yo Intermittent Recovery Level 1 Ice Hockey Test, Yo-Yo IR1-IHmax). Large differences in on-ice performances were demonstrated between Finnish and Danish elite players for agility, 10- and 30-m sprint performance (2-3%, P ≤ 0.05), and Yo-Yo IR1-IHmax performance (15%, P ≤ 0.05). By contrast, no differences (P > 0.05) were present between elite players for CMJ ability or body composition. However, elite players possessed more body and muscle mass than U20 players. Finally, the Finnish U20 cohort had a similar performance level as the Danish elite players and superior 10-m sprint performance, whereas the Danish U20 level was inferior to the other groups in every performance assessment (P ≤ 0.05). In conclusion, on-ice speed and endurance differ markedly between elite players of 2 different national standards with no distinction in body composition or CMJ ability. Moreover, the most consistent difference between U20 and senior elite players was related to body and muscle mass. These results highlight the usefulness of on-ice assessments and suggest the importance of on-ice high-intensity training in elite players in addition to training targeted the development of lean body mass in youth prospects.

Bone Health, Body Composition and Physiological Demands in 70-85-Year-Old Lifelong Male Football Players.

The effects of lifelong football training on bone health, body composition and physiological demands were evaluated. A total of 20 veteran football players (VPG; 73.4 ± 3.7 years) and 18 untrained age-matched men (CG; 75.6 ± 4.2 years) were enrolled. Whole-body and regional dual-energy X-ray absorptiometry scans of arms, legs, proximal femur and lower spine (L1-L4) were recorded in all participants. We observerd higher bone mineral density (BMD) in the whole-body, arms and femoral regions and higher bone mineral content (BMC) in the legs and lower spine compared to the CG (p < 0.05), also higher total lean body mass (p < 0.05) and lower total body fat percentage (p < 0.05), were found. No differences in food habits were evidenced between the VPG and the CG, as evaluated using 3-day food records. Resting heart rate (RHR), blood pressure (BP) and activity profile during a football match were recorded using a global positioning system only in the VPG. The mean heart rate (HR)of theoretical maximal HR (ThHRmax), and peak of ThHRmax were 83.9 ± 8.6% and 98.6 ± 10.2%, respectively; the mean of total distance covered was 3666 ± 721 m, and the means of accelerations and decelerations were 419 ± 61 and 428 ± 65, respectively. Lifelong participation in football training improves regional BMD and BMC in legs, femur and lumbar spine compared to the CG. A high number of intense actions in term of HR and accelerations and decelerations suggests an elevated energy expenditure that in turn correlates to the healthier body composition observed in the VPG compared to the CG.

The Faroe Islands COVID-19 Recreational Football Study: Player-to-Player Distance, Body-to-Body Contact, Body-to-Ball Contact and Exercise Intensity during Various Types of Football Training for Both Genders and Various Age Groups.

We determined player-to-player distance, body-to-ball contact, and exercise intensity during three training modalities in various football populations. 213 participants were recruited, ranging from 9-year-old boys to young men and 11-year-old girls to middle-aged women. All groups were analysed with video-filming and GPS-based Polar Pro monitors during three types of football training for 20 min, i.e., COVID-19-modified training (CMT) with >2-metre player-to-player distance, small-sided games (SSG), and simulated match-play with normal rules (SMP), in randomised order. Time spent in a danger zone (1.5 m) per-percent-infected-player (DZ PPIP) ranged from 0.015 to 0.279% of playing time. DZ PPIP for SSG was higher (P < 0.05) than CMT and SMP. The average number of contacts (within 1.5 m) with a potentially infected player ranged from 12 to 73 contacts/hour. SSG had more (P < 0.05) contacts than CMT and SMP, with SMP having a higher (P < 0.05) number of contacts than CMT. Time/contact ranged from 0.87 to 3.00 seconds for the groups. No player-to-player and body-to-ball touches were registered for CMT. Total player-to-player contacts were 264% higher (P < 0.05) in SSG than SMP, ranging from 80 to 170 and 25 to 56 touches, respectively. In all groups, a greater total distance was covered during SMP compared to CMT (38-114%; P < 0.05). All groups performed more high-intensity running (33-54%; P < 0.05) and had higher heart rates during SMP compared to CMT. Different types of football training all appear to exert a minor COVID-19 infection risk; however, COVID-19-modified training may be safer than small-sided game training, but also match-play. In contrast, exercise intensity is lower during COVID-19-modified training than match-play.

Danger zone assessment in small-sided recreational football: providing data for consideration in relation to COVID-19 transmission.

During the COVID-19 pandemic, physical inactivity has increased, and a wide range of sporting activities locked down, with possible long-term implications for public health. Football is the most popular sport worldwide, and recreational football training leads to broad-spectrum health effects. Football is, however, deemed a contact sport with frequent close contact important to consider during COVID-19 pandemic. OBJECTIVES: This study investigated time spent with close contact (danger zone (DZ) within 1.5 m), number of contacts and time per contact, and compared game formats in recreational small-sided football games for young and adult male football players. METHODS: Movement analyses were performed on 10 Hz Global Positioning System (GPS) data collected during various small-sided football games prior to the COVID-19 outbreak. RESULTS: Time spent in the DZ was 4.3-7.9 s/h per per cent infected players, corresponding to 34.3-114.8 s/h if one player was infected. Number of contacts with one infected player was 23.5-87.7 per hour, with an average contact time of 1.1-1.4 s, and a total number of contacts of 311-691 per hour with all players. 53%-65% of all contacts were shorter than 1 s and 77%-85% shorter than 2 s. Trivial to small effects were found for number of participants and area per player, whereas standard of play and playing with/without boards had no effect. CONCLUSION: This study demonstrated that during small-sided football limited time is spent within DZ and that player contacts are brief. Recreational football may therefore more appropriately be deemed as sporting activity with brief, sporadic contact.