Michael E. O’Connell, Kyle E. Lindley, John O. Scheffey, Alex Caravan, Joseph A. Marsh, and Anthony C. Brady
Long-term training effects of weighted ball throwing programs have been well documented. However, the mechanisms that facilitate these effects are poorly understood. The purpose of this study is to investigate within-session effects of throwing overload and underload baseballs to provide mechanistic evidence for weighted baseball training methods. Twenty-six collegiate- and professional-level baseball pitchers aged 20–30 years (mean age 23.5 [2.7] y) participated in a biomechanical evaluation while pitching a series of leather weighted baseballs. A 1-way repeated-measures analysis of variance was used to evaluate the intrasubject effect of ball weight on a total of 15 kinematic, kinetic, and performance parameters. Ball weight significantly affected pitch velocity, maximum elbow flexion, maximum pelvis rotation velocity, maximum shoulder internal rotation velocity, maximum elbow extension velocity, and anterior trunk tilt at ball release. None of the measured arm joint kinetics were significantly affected by ball weight. Training with 3- to 7-ounce (85- to 198-g) baseballs can be used to work on increasing pitching velocity without increasing throwing arm joint kinetics.
Mark Hollands, Fuengfa Khobkhun, Amornpan Ajjimaporn, Rebecca Robins, and Jim Richards
A limitation of the ability to rotate the head with respect to the upper body has been associated with turning problems; however, the extent of head constraints on whole-body coordination has not been fully determined. The aim of this study was to limit head on body rotation and observe the effects on whole-body coordination during standing turns at various speeds. Twelve participants completed standing turns at 180°. A Vicon motion system and a BlueGain Electrooculography system were used to record movement kinematics and measure horizontal eye movements, respectively. All participants were tested at 3 randomized speeds, and under 2 conditions with or without their head constrained using a head, neck, and chest brace which restricted neck movement. A repeated-measures analysis of variance found a significant main effect of turning speed on the onset latency of all segments, peak head–thorax angular separation, and step characteristics. Constraining the head rotation had multiple significant effects including delayed onset latency and decreased intersegmental coordination defined as peak head segmental angular separations, increased total step and step duration, and decreased step size. This indicates the contribution of speed, head, and neck constraints, which have been associated with falls during turning and whole-body coordination.
Paul N. Goncharow and Shawn M. Beaudette
The purpose of this research was to evaluate the algorithm DeepLabCut (DLC) against a 3D motion capture system (Vicon Motion Systems Ltd) in the analysis of lumbar and elbow flexion–extension movements. Data were acquired concurrently and tracked using DLC and Vicon. A novel DLC model was trained using video data derived from a subset of participants (training group). Accuracy and precision were assessed using data derived from the training group as well as in a new set of participants (testing group). Two-way analysis of variance were used to detect significant differences between the training and testing sets, capture methods (Vicon vs DLC), as well as potential higher order interaction effect between these independent variables in the estimation of flexion–extension angles and variability. No significant differences were observed in any planar angles, nor were any higher order interactions observed between each motion capture modality with the training versus testing data sets. Bland–Altman plots were used to depict the mean bias and level of agreement between DLC and Vicon for both training and testing data sets. This research suggests that DLC-derived planar kinematics of both the elbow and lumbar spine are of acceptable accuracy and precision when compared with conventional laboratory gold standards (Vicon).
Michael VanNostrand, Brittany Belanger, Gabriel Purin, Susan L. Kasser, and Michael Cannizzaro
The present study expands on current understanding of dual-task cognitive-motor interference, by including cortical activation measures to both traditional and ecologically valid dual-task paradigms. Fifteen individuals with multiple sclerosis and 14 control participants underwent mobility testing while wearing functional near-infrared spectroscopy. In the absence of increased prefrontal cortical activation, subjects with multiple sclerosis performed significantly worse on measures of cognition under both single- and dual-task conditions. These findings suggest that persons with multiple sclerosis may be unable to allocate additional cortical resources to cognition under dual-task conditions, leading to significant cognitive-motor interference and decrements in performance. This study is the first to investigate cortical activation across several commonly used and ecologically valid dual-task assessments.
Heather M. Hamilton and Rumit Singh Kakar
Sex-based analyses are important when studying running kinematics. Females experience a unique aging process and demonstrate differences in running biomechanics from males. The purpose was to determine the relationship between age and running kinematics in female runners. Forty-six female runners (18–65 y) ran at self-selected jogging and maximal speed on a treadmill. Lower-extremity joint kinematics were calculated, and 2 principal component analyses (jogging speed and maximal speed) were performed from kinematic variables. Regression was used to examine the relationship between age and identified components, and between age and the variables with the highest loadings within these components. For jogging speed, there was a positive relationship between age and ankle varus at initial contact and a negative relationship between age and peak eversion, hip adduction, knee flexion, dorsiflexion, and hip adduction at initial contact (Ps < .05). For maximal speed, initial contact ankle frontal plane angle became more positive with age, and there was a negative relationship with age and peak eversion, dorsiflexion and knee flexion, and knee flexion and hip adduction at initial contact (Ps < .05). Primarily distal joint angles decreased with increasing age in female recreational runners at self-selected running speeds.
Jean-Francois Esculier, Jesse M. Charlton, Natasha M. Krowchuk, Julia De Pieri, and Michael A. Hunt
The objective of this study was to compare the immediate effects of modifications to footwear or cadence on lower limb biomechanics of female Masters runners. After analyzing habitual treadmill running biomechanics in 20 female runners (52.4 [8.3] y), we assessed the effects of 5 conditions: (1) barefoot running, (2) Merrell Vapor Glove, (3) Merrell Bare Access, (4) Brooks Pure Flow, and (5) increasing cadence by 10%. In comparison with habitual biomechanics, greater vertical loading rates of the ground reaction force were observed during running barefoot or with a Merrell Vapor Glove or Bare Access. There was high variability among participants as to changes in foot kinematics during the conditions. Running barefoot (−26.0%) and with a Merrell Vapor Glove (−12.5%) reduced sagittal plane knee moments, but increased sagittal plane ankle moments (both 6.1%). Increasing cadence by 10% resulted in a more modest decrease in knee flexion moments (−7.7%) without increasing peak external ankle dorsiflexion moments. When asked if they would prefer minimalist shoes or increasing cadence, 11 participants (55%) chose cadence and 9 (45%) chose footwear. Minimalist footwear decreased sagittal knee moments, but increased vertical loading rate and sagittal ankle moments. Increasing cadence may be useful to lower sagittal knee moments without increasing ankle moments.
Karen A. Smith, Robert J. Naughton, Carl Langan-Evans, and Kiara Lewis
This mixed methods study aimed to investigate weight cutting practices of female taekwon-do athletes internationally and explore their experiences of “making weight.” A survey of weight loss practices and eating behaviors was completed by 103 taekwon-do athletes from 12 countries, which illustrated that 72.5% of athletes engage in both acute and chronic weight loss practices prior to competition and that there were higher levels of disordered eating within this athletic population than nonweight cutting athletes. Semistructured interviews were conducted with five international-level competitors; thematic analysis of the interviews identified that the women in general felt weight cutting was “horrible—but worth it” and the women believed that (a) weight cutting is unpleasant, difficult, and challenging; and (b) weight cutting provides a competitive advantage. The implications of this study are that weight cutting is widespread among high-level competitive female taekwon-do athletes and this is unlikely to change given the perceived advantages. Efforts are needed to make sure that the women are knowledgeable of the risks and are provided with safe and effective means of making weight.
Satu Kaski, Monna Arvinen-Barrow, Ulla Kinnunen, and Jari Parkkari
The aim of the present study was to identify profiles of elite athlete mental well- and ill-being and study how the profiles (i.e., subgroups of athletes) differed in sport-related demands and resources. A total of 259 Finnish elite athletes (n = 170 active and n = 89 retired) completed quantitative self-report inventories. Through cluster analysis, four profiles of mental well- and ill-being were identified. Profile 1 was overrepresented by retired, older, and male athletes, and characterized by good mental well-being. Profile 2 consisted mainly of active athletes who reported mild risk for alcohol abuse. Profile 3 consisted mainly of women who displayed possible presence of an eating disorder. Profile 4 was typical of young athletes with mental ill-being. The balance between sport-related demands and resources appeared to be the healthiest in Profile 1 and worst in Profile 4. The present findings are beneficial for those who work with and/or provide psychological support to athletes.
Courtney C. Walton, Kelsey J. Lewis, James Kirby, Rosemary Purcell, Simon M. Rice, and Margaret S. Osborne
This cross-sectional study explored athlete responses to the Compassion Motivation and Action Scales Self-Compassion Scale, examining its relationship with well-being. Athlete (N = 207; mean age 27.9 years) scores were consistent with previous population means. Scores on the Compassion Motivation and Action Scales Self-Compassion Scale did not differ between elite and nonelite athletes, nor did they correlate significantly with trait competitiveness. Significant differences emerged based on athlete well-being state, with athletes categorized as “flourishing” scoring higher on the total score and all subscales of the Compassion Motivation and Action Scales Self-Compassion Scale, as compared with those with “moderate mental health” (Cohen’s ds from 0.58 to 0.92). Furthermore, the distress tolerance subscale significantly mediated the relationship between self-compassion intentions and well-being (indirect path: B = 0.034, p < .001). The results suggest that self-compassionate intentions are not enough, and athletes may need support to tolerate the distress that comes with moving toward one’s own suffering.