The dose-response relationship between biomechanical variables and the magnitude of external loads is unclear. The use of different load distributions (e.g., pack types) may confound results because of changes in torso center of mass. Therefore, we examined the relationship between load magnitude and sagittal plane lower extremity mechanics of Soldiers walking with two symmetrically distributed loads. Fourteen Soldiers marched on a force-sensing treadmill at 1.34 m/s for 10 minutes with no load (BW_00) and while wearing vest-borne loads of 15 kg (BW_15) and 55 kg (BW_55). The effects of the loads on sagittal plane joint angles and moments were compared using 1-way repeated measures analyses of variance. Compared with BW_00, knee extension moment increased with the 15- and the 55-kg loads (both p < 0.003), confirming previously reported load-related biomechanical responses. Knee moment increases during early stance appeared to be the primary means by which the lower extremity counteracted BW_15 during early stance; in contrast, hip extensors and ankle dorsiflexors appeared to be the primary muscular efforts responsible for propulsion during late stance. Findings elucidated the effects of load magnitude on lower extremity mechanics without postural changes that result from pack-related shifts in torso center of mass.

Soldiers were mostly heel strikers (87%) in this U.S. Army Combined Arms Battalion. Neither FS pattern was advantageous for increased performance or decreased incidence of running-related injury.

In most of the studies it seems that the presence of a contracture is equivalent with the presence of restriction in the range of motion (ROM) of a joint. Very little is known about risk factors for contractures. But it seems that immobility may play a pivotal role in the development of this condition. IMPLICATION FOR REHABILITATION: The prevalence of contractures in nursing home residents is estimated at 55% with significant functional and medical consequences. In most studies, which were published in the last 10 years, the presence of a contracture is equivalent with the presence of restriction in the range of motion of a joint. Immobility seems to play a role in the development of contractures. Potential avenues to prevention of contractures and subsequent functional limitations are exercise programmes for and maintenance of mobility of the elderly.