Effects of thigh muscle activity patterns on blood pressure and edema during interrupted sitting in overweight and obese men.

PURPOSE

This study compared the effects of different muscle activity patterns on blood pressure and lower leg edema during interrupted sitting in overweight and obese men.

DESIGN

Randomized four-arm cross-over experimental study.

METHODS

Eighteen overweight and obese men (21.0 ± 1.2 years; 28.8 ± 2.2 kg/m) took part. The four interventions were uninterrupted sitting for 8.5 h (SIT) and interruptions in sitting with 30-min walking at 4 km/h (ONE), sitting with 3-min walking at 4 km/h (WALK) or squatting (SQUAT) every 45 min for 10 times. Blood pressure was measured every 45 min. Lower leg volume was measured using water displacement method at the beginning and immediately after the experiment to examine lower leg edema. Thigh muscle electromyogram (EMG) amplitude and EMG activity duration were used to predict the effects on blood pressure and lower leg edema in generalized linear mixed effects models.

RESULTS

Mean systolic blood pressure was reduced by 2.54 mmHg (95% CI - 4.47 to - 0.62, P = 0.010) in WALK relative to SIT. The changes of lower leg volumes were reduced by 70.34 ml (- 112.78 to - 27.91, P = 0.002) in WALK and 62.49 ml (- 104.92 to - 20.06, P = 0.005) in SQUAT relative to SIT. Increased thigh muscle EMG amplitude was associated with lower systolic blood pressure (- 1.02 mmHg [- 1.79 to - 0.25], P = 0.010). Longer EMG activity duration was associated with decreased lower leg edema (- 1.02 ml [- 1.83 to - 0.21], P = 0.015).

CONCLUSION

Frequent interruptions to prolonged sitting confer distinct health benefits through specific muscle activity patterns, providing potential targets for interventions.