Effects of age on neuromuscular knee joint control.

Age-related changes in neuromuscular function may have adverse effects on hamstring reflex activity and may impair knee joint stability. The aim of this study was to investigate whether increasing age affects hamstring short latency responses (SLR), medium latency responses (MLR), and anterior tibial translation. In 40 healthy subjects ranging from 20 to 70 years of age we assessed hamstring muscle latencies and integrals for both hamstring reflex components (SLRs and MLRs) as well as anterior tibial translation in order to quantify knee joint stability in response to induced tibial translation during stance. The results showed no significant differences within the subject population in hamstring SLR and MLR latencies and integrals or anterior tibial translation. More precisely, regression analysis did not reveal any correlation between age and the aforementioned parameters. Our findings suggest that functional knee stability in terms of anterior tibial translation appears to be unaffected from people 20 to 70 years of age. Thus, as compared with younger people, older people - at least those under 70 years of age - do not appear to have a higher risk of ligamentous knee injuries associated with hamstring dysfunction. Further studies should be conducted to assess whether the present findings also apply to dynamic real-world situations. This would improve the understanding of the relationship between knee stability and ageing.