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There has been little scientific investigation of the impact of dance shoes on foot motion or dance injuries. The pointed (plantar-flexed) foot is a fundamental component of both the technical requirements and the traditional aesthetic of ballet and jazz dancing. The aims of this study were to quantify the externally observed angle of plantar flexion in various jazz shoes compared with barefoot and to compare the sagittal plane bending stiffness of the various jazz shoes. Sixteen female recreational child dancers were recruited for 3D motion analysis of active plantar flexion. The jazz shoes tested were a split-sole jazz shoe, full-sole jazz shoe, and jazz sneaker. A shoe dynamometer measured the stiffness of the jazz shoes. The shoes had a significant effect on ankle plantar flexion. All jazz shoes significantly restricted the midfoot plantar flexion angle compared with the barefoot condition. The split-sole jazz shoe demonstrated the least restriction, whereas the full-sole jazz shoe the most midfoot restriction. A small restriction in metartarsophalangeal plantar flexion and a greater restriction at the midfoot joint were demonstrated when wearing stiff jazz shoes. These restrictions will decrease the aesthetic of the pointed foot, may encourage incorrect muscle activation, and have an impact on dance performance.

The aim of the current study was to investigate the EMG activity of pectoralis major and latissimus dorsi muscles during the pullover exercise. Eight healthy male volunteers took part in the study. The EMG activity of the pectoralis major and that of the latissimus dorsi of the right side were acquired simultaneously during the pullover exercise with a free-weight barbell during both the concentric and eccentric phases of the movement. After a warm-up, all the subjects were asked to perform the pullover exercise against an external load of 30% of their body weight, during 1 set × 10 repetitions. The criterion adopted to normalize the EMG data was the maximal voluntary isometric activation. The present findings demonstrated that the barbell pullover exercise emphasized the muscle action of the pectoralis major more than that of the latissimus dorsi, and the higher activation depended on the external force lever arm produced.

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).

Breast cancer affects one in 8 females with a 5-year survival rate of 89%. Up to 72% of breast cancer survivors have trouble with activities of daily living (ADL) following treatment. Increased time-from-treatment improves some measures of function, yet ADL limitations persist. Therefore, this study assessed the effect of time-from-treatment on upper extremity kinematics during ADLs in breast cancer survivors. Twenty-nine female breast cancer survivors were divided into 2 groups: <1 year (n = 12) and 1–2 years (n = 17) from treatment. Kinematics were collected during 6 ADL tasks, and humerothoracic joint angles were quantified. A 2-way mixed analysis of variance assessed the effects of time-from-treatment and arm on maximum angles for each ADL. Decreased maximum angle existed for breast cancer survivors with increased time-from-treatment during all ADLs. Breast cancer survivors in the 1–2 years group used ∼28° to 32° lower elevation, ∼14° to 28° lower axial rotation, and ∼10° to 14° lower plane of elevation range across tasks. Decreased ranges of arm movement during ADLs with increased time-from-treatment may reflect compensatory movement strategies. Recognizing this shift in strategies and accompanying underlying disease progression can help inform responses to functional performance limitations in breast cancer survivors as delayed effects are present posttreatment.

The objective of this study was to compare a number of variables derived from the vertical and horizontal force components between loaded countermovement jumps performed in a Smith machine (SM modality; vertically restrained jumps) and with free weights (FW modality; unrestrained jumps). Twenty-three recreationally trained individuals, 6 women and 17 men, performed on a 3D force platform 5 maximal countermovement jump trials against 3 external loads (30%, 50%, and 70% of the SM 1-repetition maximum) using the SM and FW jumping modalities on separate sessions. The SM modality promoted greater values for virtually all the variables derived from the vertical force component (maximal force, maximal and minimum velocity, and impulse) and also shorter durations of the braking and propulsive phases. Regardless of the countermovement jump phase (braking or propulsive), the impulse directed toward the backward direction was always considerably greater for the SM compared with the FW modality. These results evidence that for recreationally trained individuals, the SM modality could be more effective to increase the general force capacity of the leg muscles due to increased external stability, while the FW modality is preferable when the orientation of force application is a crucial consideration, as it reduces the horizontal force component.