This study analyzed the systematic bias, limits of agreement (LoA), and association between the anaerobic threshold (AT) and the heart rate deflection point (HRDP) in athletes.
A systematic search in EBSCOhost, PubMed, and Scopus was performed to identify studies analyzing AT (via blood lactate or gas exchange) and HRDP in athletes. Specific participant characteristics, exercise protocols, and analytical procedures were recorded. A random-effects meta-analysis evaluated agreement and bias between HRDP and AT. Systematic bias between AT and HRDP was assessed for heart rate (beats/min), running speed (km/h), and power output (W). Furthermore, meta-regression analysis was computed by considering the design of exercise protocols as well as methods applied to examine the AT (i.e., second lactate or ventilatory threshold), and the HRDP (i.e., mathematical detection or. visual analysis) as potential moderators.
Twenty-five studies were selected, covering athletes such as runners, cyclists, mountain runners, and rowers. Significant systematic bias was found in heart rate (2.9 beats/min) and running speed (0.7 km/h), but not in power output (4.2 W). Wide limits of agreement were noted across all metrics, and the exercise protocol significantly influenced bias in speed. Methods applied to examine the AT and the HRDP did not influence the systematic bias between exercise thresholds.
Significant bias, wide LoA, and large estimation errors suggest HRDP is not reliable for non-invasive AT estimation in athletes. Standardized protocols and further exploration of population-specific moderators are necessary to enhance its utility as a practical tool for monitoring training adaptations.
Lower limb injury rates have increased dramatically in line with the rise in female athletes participating in team sports where larger training demands are required for higher performing athletes, increasing exposure to injury. One modifiable and intrinsic risk factor associated with lower limb injuries is muscle strength, measured through single joint machine isokinetic dynamometry (MID) and handheld dynamometry (HHD).
The purpose of this review was to explore which protocols have been used for MID and HHD lower limb muscular strength assessments, highlighting the test–retest reliability, for the female team sport athlete population.
A review of the literature was conducted using Medline, PubMed, Scopus, SPORTDiscus and Web of Science databases. Of the 26,032 articles identified, 107 were included for analysis.
Seated knee flexion/extension was the most common test performed with a similar protocol while hip and ankle joint muscle group tests were performed across two to four positions. Test–retest reliability was poor to excellent for hip and knee tests and only reported in four studies (intraclass correlation coefficients = 0.25–0.98).
The same protocol was followed primarily for MID knee flexion/extension (73 studies). However, differences were observed for MID and HHD hip and ankle joint protocols resulting in variable data that could not support dynamometry protocol recommendations for this population. Research exploring the reliability and validity of protocols including measurement equipment may improve the worth of existing data and assessment protocols to support injury and performance strategies in the future.
A ball-kicking motion requires a coordinated sequencing of all body segments for maximum ball release speed. Evidence of the role of upper body rotations and motor coordination during a ball-kicking motion is inconsistent among existing evidence. This study aimed to systematically review the role of upper body rotations on all modes of ball kicking and performance metrics. A comprehensive search of seven electronic databases from the inception was conducted. Studies reporting on the relationships between upper body rotation, and ball-kicking performance were included. From 1486 potentially relevant studies, we analysed 27 studies involving 457 participants. These studies encompassed instep soccer kicks (n = 21), inside-of-the-foot soccer kicks (n = 1), rugby place kicks (n = 4) with a stationary ball, and a volley kick (n = 1). Methodological quality assessment was performed using Standard Quality Assessment Criteria. Our results provide moderate evidence that increasing thoracolumbar rotations along the longitudinal axis and the transverse plane can enhance ball-releasing velocity through a "whip-like effect" based on the kinetic link principle. However, to gain a comprehensive understanding, further research is needed to explore the effects of timing and the ranges of motion of all relevant upper and lower body segments on ball release velocity and its potential influence on ball release accuracy. The current coaching manuals do not emphasise the significance of upper body rotation, indicating a pressing requirement for revisions in training guidelines to enhance ball-kicking performance.
Dynamic strength index (DSI) and percentage of isometric mid-thigh pull (IMTP) peak force (PF) produced during early epoch, expressed as a percentage of net PF (%PF), are useful strength assessments to evaluate an athlete’s training status. Due to the similarity in diagnosis that the DSI ratio and %PF provides, it is not known whether %PF can reflect closely to an athlete’s DSI ratio. Therefore, the aim of this study is to establish the relationship between DSI and %PF.
Thirty-seven national athletes (age = 22.9 ± 3.12 years; height = 1.73 ± 0.08 m; body mass = 69.1 ± 10.68 kg) were recruited for this study. Participants performed the countermovement jump test (CMJ) and isometric mid-thigh pull (IMTP) during both familiarisation and testing sessions. IMTP and CMJ force–time variables were collected to compute the DSI ratio and %PF for analysis.
Trivial to small correlations between DSI and %PF was observed across all epochs (50 ms: r = 0.09, 95% CI − 0.241–0.402, P > 0.598; 100 ms: r = − 0.021, 95% CI − 0.343–0.305, P > 0.9; 150 ms: r = − 0.058, 95% CI − 0.375–0.271, P > 0.734; 200 ms: r = 0.126, 95% CI − 0.207–0.432, P > 0.458).
DSI ratio and %PF are two distinct monitoring tools and not interchangeable. Both DSI and the percentage of IMTP net PF at early time points are useful in evaluating athletes’ previous training phases and current physical performance.
The purpose of this study was to determine the effect of sampling frequency on the 90–90° (90-degrees hip and knee flexion) isometric hamstring assessment. Thirty-three elite female soccer players (age: 18.7 ± 3.7 years; height: 158.3 ± 5.9 cm; body mass: 62.8 ± 5.5 kg) performed three unilateral trials on a single occasion of the 90–90° isometric hamstring assessment. Force-time data were collected using force plates at 1000 Hz and down sampled to 500-, 250-, and 100 Hz. Peak force (N), force (N) at 100- and 200 ms and average rate of force development (aRFD) (N/s) over a 100- and 200 ms epoch were calculated. A repeated measures of analysis of variance and effect size was used to compare means. Excellent absolute and good relative reliability was observed for peak force across all sampling frequencies. Force at 100- and 200 ms and aRFD over 100 ms and 200 ms resulted poor-moderate relative reliability and poor-excellent absolute reliability. No significant trivial differences were observed for peak force between sampling frequencies (P > 0.05, Cohen’s d = 0.02–0.12). A significant difference (P < 0.001) was identified in 500, 250 and 100 Hz, with small-moderate and small-large increases in force at set time points and aRFD, respectively, in comparison to 1000 Hz (d = 0.21–2.00). Higher sampling frequencies (> 500 Hz) reduces the reliability of time dependent force characteristics, with minimal effect on peak force. Regular monitoring of peak force can be performed with higher sampling frequencies, but lower sampling frequencies would be beneficial to collect reliable rapid-force generating measures.
To describe and compare the movement patterns, anthropometric and physical characteristics of male and female Touch players; and examine the relationships between Functional Movement Screening (FMS™) scores and the anthropometric and physical characteristics.
This was a cross-sectional study with 35 elite Touch players (18 males, age = 24.7 ± 4.9 years; 17 females, age = 26.7 ± 5.2 years). Anthropometric (stature, body mass) and physical characteristics (sprint times, glycolytic change-of-direction test, and countermovement jump (CMJ) flight time and peak power) were assessed alongside movement patterns using the FMS™ battery. Data were analysed for between-sex differences (independent t-test, Mann–Whitney U) and relationships (Spearman’s correlation coefficient).
Between-sex differences in body mass (t = 6.082, P < 0.001), stature (t = 9.247, P < 0.001), CMJ flight time (t = 3.576, P = 0.001), relative CMJ peak power (t = 6.578, P < 0.001), 10 m sprint time (t = 15.861, P < 0.001), glycolytic change of direction test time (t = − 11.831, P < 0.001) and Yo–Yo IR1 (t = 6.842, P < 0.001) were observed. There were minimal differences for deep squat (Z = − 1.036, P = 0.443), in-line lunge (Z = − 1.284, P = 0.303), shoulder mobility (Z = − 0.173, P = 0.883), trunk stability push-up (Z = − 0.896, P = 0.483) and rotary stability (Z = − 1.537, P = 0.273). The correlation between total and individual FMS™ scores with anthropometric and physical characteristics ranged from trivial-to-moderate (r = − 0.502 to 0.488).
The lack of difference for the FMS™ composite score and small-to-trivial differences in individual scores allows a comparison between mixed populations within Touch. Whilst many of the correlations were trivial-to-small, there were differences between sexes in the associations and evidence that improvements in functional deficiencies could translate into improved physical performance.
Sprinting is the most common activity associated with hamstring strain injuries in soccer. However, the potential mechanisms for hamstring strain injuries during the initial acceleration phase of sprinting are unclear. Therefore, this study aimed to characterize the kinematics and activation of the hamstring muscles in soccer players to clarify the potential mechanism of hamstring strain injury.
Ten male soccer players with no lower limb injuries in the past year were recruited for this study. Each participant was instructed to perform a minimum of three successful 15-m sprints. Hamstring kinematics and activations were estimated by employing musculoskeletal modeling and wireless electromyography to define potential injury mechanisms.
During the initial acceleration phase, the hamstring muscles undergo great strain and high activation levels in the late swing and early-stance phases. The hamstring muscles experienced great strain and overload during the late swing and foot strike of the running cycle. In addition, the biceps femoris long head was significantly more stretched than the semimembranosus and semitendinosus (P < 0.01 for semimembranosus and P < 0.05 for semitendinosus).
Based on these results, hamstring injuries are likely to occur during the late swing and early stance of the running cycle, with the biceps femoris long head being more susceptible to injuries than other hamstring muscles.
“Cuban Motion” (CM) is a term often used to label a basic movement of many Latin-American dances, such as salsa and bachata. It is characterized by a cyclical and rhythmic flexion and rotation of the pelvis, accompanied by ample movements of the spine and lower limbs. Since Latin dances are considered both a recreational activity and a kind of healthy gymnastics for young and older subjects, a biomechanical analysis of the CM was performed to quantitatively assess the main features of this movement, from joint kinematics to muscle activations.
The study combined experimental acquisitions with a Vicon Motion Capture system and musculoskeletal analyses in OpenSim. Only one subject was considered, an instructor of Latin dances, who was equipped with 55 retro-reflective markers, according to the Full Body CGM2.5 marker set. Data were processed in OpenSim, using the ThoracoLumbar model (111 DoFs and 620 musculo-tendon actuators).
The cycle of the CM and its main events were defined. Results showed a wide RoM of many joints, with correlations between hip and knee flexion angles and among list, between hip adduction and shoulder flexion. The main role of the iliopsoas and the ileus costalis muscles was observed.
The current study quantified the CM as a physical exercise using a biomechanical approach similar to a gait analysis. The main kinematic and kinetic features were described, also providing an estimation of the muscle activations and joint reactions, derived from simulation activity in OpenSim. The main limitation of this study is the focus on a single subject, but this step was necessary to define a context and guidelines for future investigations, where we are going to compare èlite vs. novices and male vs. female dancers.
Laser Run combines running and shooting with a laser pistol in multiple laps with high cardio-vascular stress. The aim of this study was to analyze the impact of shooting rate, shooting rhythm, heart rate, and core stability on the overall performance.
During a qualification race with 23 elite athletes heart rate and shooting performance were measured. The shooting rate and rhythm were then calculated and trunk strength endurance was determined in a separate test.
Firing an average of 10.2 ± 3.9 shots per lap, the athletes spent a mean of 23.0 ± 12.0 s at the shooting range. The mean shooting rate was approximately 2.4 s between two shots. The results indicated a regular shooting rhythm to be more important than high shooting rate. The variation of the shooting rate showed a strong correlation with the overall shooting performance (r = 0.77). Athletes shoot at a heart rate close to 95% of their maximum heart rate. However, deviations do not seem to influence on the shooting performance, whereas core strength endurance obviously has a strong impact on shooting performance (r = −0.57).
Athletes must train to shoot with high heart rates and find a balance between high shooting rate and precision. A constant shooting rhythm and good core stability appear to be particularly important for high performance.