Stretch reflex variation in the relaxed and the pre-activated quadriceps muscle of normal humans

Abstract

The stretch reflex to patellar tendon taps was quantified by force measurements at the ankle in 7 normal subjects. In each experiment the stretch reflex was elicited from 14 consecutive stretches by two types of hammers (an ordinary hand-held hammer and a motorized hammer) in the relaxed and the pre-activated quadriceps muscle. The coefficient of variation for the 14 stretch reflexes fell from 54% in the relaxed muscle to 39% in the contracting muscle (p less than 0.05). The stretch reflex varied less between the different levels of active contraction than between the relaxed state and the contracted level (p less than 0.05). The experiment was repeated in all subjects and at all contraction levels. The coefficient of variation of the mean for the two experiments fell non-significantly from a mean value of 27% in the relaxed muscle to 14% in the contracting muscle. The coefficients of variation for the two hammers were almost identical. It is concluded that quantification of the stretch reflex can be made more precisely in the contracting muscle.

Modulation of reflex responses in activated ankle dorsiflexors differs in healthy young and elderly subjects

“…The absence of a significant age-related decrement in H-reflex area contrasts with some studies (Angulo-Kinzler et al 1998;Kido et al 2004;Sabbahi and Sedgwick 1982) but not others (Kawashima et al 2004;Scaglioni et al 2003). As already mentioned, this discrepancy may be partly due to the variability of reflex responses, particularly when they are recorded at rest (Toft et al 1991). For this reason and because it is more functionally relevant (Stein and Thompson 2006), we recorded stretch and H-reflex responses during submaximal contractions.…”

VMO-VL reflex latency difference in osteoarthritic knees and controls

“…A vibration sensor (Maplin Electronics, Barnsley, South Yorkshire, UK) attached to the hammer arm produced a square wave time marker on the recording on impact. Ten patellar taps were delivered at random time intervals (10 Á/20 s apart) to avoid habituation or fatigue (18,19). Data were sampled at 2048 Hz using a physiological data acquisition system (Biopac) comprising an MP100 workstation with a high-level transducer HLT100 and dedicated analysis software (AcqKnowledge 3.5.3, Biopac).…”

Quadriceps force generation in patients with osteoarthritis of the knee and asymptomatic participants during patellar tendon reflex reactions: an exploratory cross-sectional study

“…A vibration sensor (Maplin Electronics, UK) attached to the hammer arm and connected to the MP100 workstation produced a square wave time marker on the recording on impact. Ten taps to the patellar tendon were delivered at random time intervals (10 to 20 s apart) to reduce habituation or fatigue [22,23]. Data were sampled at 2048 Hz using a physiological data acquisition system (BIOPAC Inc., USA) comprising the MP100 workstation with a high level transducer HLT100 and dedicated analysis software (AcqKnowledge 3.5.3).…”