Classroom-Integrated Kettlebell Training: Effects on Motor Performance, Attention, and Health in Primary School Children.

Classes were not randomized; teachers chose allocation in two schools, and one class was automatically assigned to the intervention group. Participant counts differ across the paper: 93 participated, 94 were assigned, 76 completed post-test, and 78 remained after attrition. Sample size was not based on a priori power calculations. No single primary outcome is stated, and several outcomes were examined, so the sprint result may reflect multiple comparisons. Training intensity was not monitored, so actual exertion during sessions is uncertain. Physical activity outside school was not measured, so total daily activity is unknown. Socioeconomic background distribution was not assessed. The Flanker task was done in a classroom with possible distractions and no familiarization. Null attention results are therefore uncertain.

This work was supported by Starak. No other funding or conflict-of-interest details are given in the supplied text.

Do not conclude that kettlebell training alone improves strength, attention, body composition, or blood pressure. Only sprint performance showed a significant effect, the programme was added to usual physical education, and the study was not randomised.