Alternatives to in-person exercise classes and training in Germany during the first COVID-19 lockdown.

COVID-19 containment efforts in most countries included temporary closure of all non-essential services, such as sports and exercise facilities. Also in Germany, sports clubs (SC) had to close for about 2 months starting mid-March 2020. The aim of the present study was to assess what alternatives German SC developed to in-person exercise classes and training. We conducted an anonymous online survey among large German SC. Invitation was sent to 178 SC, 61 data sets could be analyzed. A total of 92% of SC have offered alternatives to in-person exercise classes and training, most of which were digital. Reasons for not offering any alternatives were the lack of financial, personal or technical resources. The large majority (82.1%) of the SC have also allowed non-club members free access to digital alternatives, and 69.6% considered keeping this freely accessible even after the restrictions have been lifted. Almost three quarters (72.3%) of the sport clubs have received no support from their regional umbrella sports organization. In light of the dynamic development of the COVID-19 pandemic, SC must be prepared to offer alternatives to in-person exercise classes and training also on the middle term. These efforts should be supported by sports organizations and communities.

Validity of and recommendations for knee joint acoustic assessments during different movement conditions.

Knee joint sounds contain information on joint health, morphology and loading. These acoustic signals may be elicited by further, as yet unknown factors. By assessing potential elicitors and their relative contributions to the acoustic signal, we investigated the validity of vibroarthrographic assessments during different movement conditions with the aim to derive recommendations for their practical usage. Cross-sectional study. Nineteen healthy participants (24.7 ± 2.8 yrs, 7 females) performed five movements: level walking, descending stairs, standing up, sitting down, and forward lunge. Knee joint sounds were recorded by two microphones (medial tibial plateau, patella). Knee joint kinematics and ground reaction forces were recorded synchronously to calculate knee joint moments (Nm/Kg). The mean amplitude (dB) and the median power frequency (Hz) were determined. A repeated measures mixed model investigated the impact of potential predictors (sagittal, frontal, transverse plane and total knee joint moments, knee angular velocity, age, sex, body mass index (BMI) and Tegner Activity Score (TAS)). Most of the amplitudes variance is explained by between-subject differences (tibia: 66.6%; patella: 75.8%), and of the median power frequencies variance by the movement condition (tibia: 97.6%; patella: 98.9%). The final model revealed several predictor variables for both sensors (tibia: sagittal plane, frontal plane, and total knee joint moments, age, and TAS; patella: sagittal plane knee moments, knee angular velocity, TAS). The standardization of the execution of the activities, a between-group matching of variables and the inclusion of co-variates are recommended to increase the validity of vibroarthrographic measurements during different movement conditions of the knee joint.