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This study examined physiological recovery between repeated tennis drills in elite adolescent tennis players. Ten tennis players (5 males, 5 females; age 17 ± 2 years) underwent treadmill testing to establish maximal physiological characteristics. Several days later participants completed three standardized on-court tennis drills with fixed rest intervals, during which physiological parameters were monitored. A one-way repeated-measures ANOVA was used to compare physiological responses across the three drills. [Formula: see text] utilization stayed above 75% in all drills, peaking during the first drill (p = 0.003). During recovery, [Formula: see text] utilization decreased from 58 ± 8% in the first recovery to 50 ± 9% (p = 0.018) and 47 ± 12% (p = 0.022) in the second and third recovery, respectively. The respiratory exchange ratio (RER) stayed below 1.0 during drills, while increasing during recovery periods, (1.07 ± 0.08, 1.00 ± 0.01, 1.04 ± 0.05; p = 0.014). Ventilatory equivalents for oxygen ([Formula: see text]) were stable (p = 0.054), while those for carbon dioxide ([Formula: see text]) increased progressively for each recovery period (29.5 ± 3.6, 31.5 ± 3.8, 32.3 ± 4.3; p < 0.001). Blood lactate concentration differed significantly across recovery periods (p = 0.035) with the lowest value in recovery period two (5.9 ± 2.0, 4.9 ± 1.9 and 5.6 ± 2.0 mmol·l-1). These findings highlight a sustained metabolic demand extending into the recovery phase during standardized tennis drills, characterized by substantial [Formula: see text] utilization and elevated respiratory compensation. This suggests a significant anaerobic contribution and underscores the intensity of the physiological load imposed even after exercise cessation.

Management of sports-related concussion – a stepwise rehabilitation protocol

Early recognition and management of sports-related concussion (SRC), including removal from the sports activity, is essential for player safety and to prevent longterm symptoms. A graduated, stepwise rehabilitation protocol is implemented to allow the athlete to return to sports. In 2022, the 6th international consensus statement on concussion in sports was presented, which has now been adapted to Swedish conditions. In the present overview, the updated recommendations for SRC in athletes are summarized.

PURPOSE: This study aimed to investigate how pole length, incline, and skiing intensity affect lower back muscle activation in elite cross-country skiers. This addressing a critical gap in understanding the biomechanical demands and risk of low back pain of double poling (DP).

METHOD: Eleven elite cross-country skiers performed skiing trials on a treadmill, varying in incline (flat vs. 6°), intensity (two self-selected speeds, training speed and racing speed), and pole lengths. Muscle activity was measured by surface electromyography on the erector spinae thoracic and lumbar muscles, on the left and right side. A motion capture system was used for kinematic analysis of the lower back-pole moment arm and the hip angle during the DP cycle.

RESULTS: Compared to men, female skiers had a significantly higher (p < 0.001), overall muscle activation for the m. erector spinae lumbar on both the left and right side (26% of MVC vs. 15% of MVC, and 28% of MVC vs. 22% of MVC, for the left and right side, respectively). No correlations were found, neither between muscle activation to the lower back-pole moment arm, or to the hip angle.

CONCLUSION: The findings suggest that female skiers experience significantly higher lumbar erector spinae activation during DP, potentially indicating greater susceptibility to back-related issues. The results also highlight the need to tailor training and right adapted equipment to mitigate lower back stress, especially in flat terrain high-intensity conditions. The asymmetrical muscle activity and gender differences underscores the need for further investigation into biomechanical factors influencing back muscle engagement in cross-country skiing.

Purpose: This study aimed to differentiate external and internal training loads during on-snow biathlon training by adding an accelerometer-derived metric.

Methods: Eleven adolescent athletes were fitted with a combined heart rate (HR) and accelerometer to be worn during all training sessions. Duration, HR, training impulse (TRIMP), and average net force ( AvF_Net) were used as training variables. All training was divided into either low-intensity training (LIT), or high-intensity training (HIT) based on reported intensity. The training was further categorized as training without any shooting practice (NS) or as a combination of skiing and shooting (COMB). Duration, HR, TRIMP, and AvF_Net were analyzed in a linear mixed model for the different training modalities.

Results: All training was similar in duration for LIT and HIT sessions (p = .0521) and NS and COMB sessions (p = .988). TRIMP did not differentiate between LIT or HIT training (p = .350) or for NS compared to COMB (p = .298). While AvF_Net decreased during COMB compared to NS during LIT sessions (p < .001) it remained similar during HIT training (p = 1.00).

Conclusion: The study's findings indicated that there were no notable differences in internal training load (TRIMP) when comparing various training intensities and modes. However, the type of training had a significant impact on AvF_Net, especially leading to a decrease during COMB sessions under LIT conditions. Incorporating an external load metric could offer a fresh approach when prescribing and evaluating training, providing deeper insights into the training load.

Purpose Tennis demands exceptional technical skills, speed, strength and endurance. Previous studies have highlighted the high energy expenditure during tennis drills due to constant directional changes. While metabolic monitoring and player tracking have been used to quantify exercise intensity and movements, mechanical efficiency (ME) in tennis remains poorly understood. This study aimed to investigate ME in tennis by combining metabolic and mechanical measurements during on-court drills.

Methods Ten elite adolescent tennis players (males n = 5, females n = 5) performed a VO2max test on a treadmill and participated in three standard tennis drills, Spanish cross, lateral and inside out. During the tennis drill, full-body kinematics were captured, and energy expenditure was measured using a portable breath-by-breath gas analysis. ME was calculated for each drill, and individual differences were examined.

Results Results revealed significant differences in energy expenditure and mechanical work between drills. ME was not associated with VO2max or running speed. highlighting the need to focus on other factors like strength, footwork technique, and neuromuscular training to enhance ME.

Conclusion This study underscores the complexity of ME in tennis, with individual variations and where factors like footwork technique, muscular strength and motor abilities might influence ME.

INTRODUCTION: Officials are essential in terms of player safety and injury prevention, especially in contact team sports such as ice hockey, where numerous fast pace and high force contacts occur. If against the rules, these collisions can result in penalties. However, there is limited literature on the inter-rater reliability of the officials' decisions. Hence, the purpose was to investigate the theoretical reliability agreement between professional ice hockey officials in the Swedish Hockey League (SHL).

METHOD: Fifty video clips with different match situations were shown to 33 professional ice hockey officials in the SHL. Each situation was shown three times and the officials had 20 s between each video clip to answer which offence and penalty they would judge. The answers were anonymously collected using an online questionnaire. Fleiss' kappa was used to assess the reliability agreement between the referees, for each situation.

RESULTS: The Fleiss' kappa values for all officials were 0.63 and 0.35 for offences and penalties, respectively. Referees and linesmen had similar kappa values for offences (0.64 vs. 0.64), as well as for penalties (0.38 vs. 0.35).

CONCLUSION: The results show that the suggested methodology can be used to identify situations where officials agree and disagree. In ice hockey, poor agreement regarding penalties can depend on the chosen offence as the rulebook limits the availability of penalties, based on the chosen offence. This can create issues, as there are situations where different offences are equally correct but will result in different penalties.

Background: Even though women's ice hockey does not permit deliberate checking between players, female players are at similar or even higher risk to sustain concussions, as male players. Several studies have investigated head impacts in ice hockey, however to the best of the authors' knowledge, no previous study has used impact monitoring mouthguards to investigate head impact exposure among professional female ice hockey players. Methods: Impact monitoring mouthguards were used to collect head impact data during games in the Swedish Women's Hockey League and in the men's Swedish J20 SuperElite League in 2020. Results: Female players had significantly higher median linear accelerations than male players (26 [19–35] g, vs. 7 [5–9] g, p ​< ​0.001, d ​= ​1.98). Female players had significant higher median rotational accelerations compared to male players (3076 [2314–4243] rad/s2 vs. 430 [281–752] rad/s2, p ​< ​0.001, d ​= ​2.398). There were no notable variances in impact distribution by location for linear or rotational accelerations among female players. Similarly, male players didn't exhibit significant differences in impact location for linear acceleration. However, impacts at the Top Front location demonstrated significantly higher rotational accelerations compared to those at Front Low and Front High positions. Conclusion: Compared to male players, female players sustain fewer but harder impacts to the head, which may explain the high occurrence of concussion in women's ice hockey. © 2024 The Author(s)

Video is the most used tool for sport performance analysis as it provides a common reference point for the coach and the athlete. The problem with video is that it is a subjective tool. To overcome this, motion capture systems can used to get an objective 3D model of a person’s posture and motion, but only in laboratory settings. Unfortunately, many activities, such as most outdoor sports, cannot be captured in a lab without compromising the activity. In this paper, we propose to use an aerial drone system equipped with depth cameras, AI-based marker-less motion capture software to perform automatic skeleton tracking and real-time sports performance analysis of athletes. We experiment with off-the-shelf drone systems, miniaturized depth cameras, and commercially available skeleton tracking software to build a system for analyzing sports-related performance of athletes in their real settings. To make this a fully working system, we have conducted a few initial experiments and identified many issues that still needs to be addressed.

Objective: To investigate the relationship between head impact characteristics and the levels of blood biomarkersassociated with brain injury, neurofilament light (NfL) and glial fibrillary acidic protein (GFAP).Methods: Four elite amateur Muay Thai athletes were equipped with impact monitoring mouthguards, collectinglinear and rotational acceleration data during a period of eight weeks. Capillary blood samples were collectedafter each period of sparring sessions to analyse the levels of NfL and GFAP.Results: On a group level, mean GFAP levels were negatively correlated to mean impacts per session (p < 0.05).Two athletes had significant correlations between head impact characteristics and the levels of NfL and/or GFAP.Conclusions: The results indicate that NfL and GFAP might responded differently to linear and rotational accelerationsand/or that the effect of different types of accelerations on brain tissue integrity is individual. Themethods used could be useful to monitor brain health in different impacts sports.