Pubblicazioni

Assessment of skeletal muscle endurance using twitch electrical stimulation and accelerometer based mechanomyography

Willingham, Thomas B; McCully, Kevin K

Abstract:

Previous studies have used twitch electrical stimulation and accelerometer-based mech-anomyography to evaluate muscle function in clinical populations. However, the repro-ducibility and validity of the methodology has not been defined. This study evaluated the reproducibility and validity of twitch electrical stimulation and accelerometer-based mech-anomyography (aMMG) as an assessment of muscle endurance. Participants were healthy males and females 21.8±1.9 years of age. Muscle twitch acceleration was measured using an accelerometer placed over the surface of the muscle. The relationship between acceleration and torque was measured during twitch stimulation of the vastus lateralis muscle. Muscle endurance of the forearm and gastrocnemius was measured during 9 minutes of twitch electrical stimulation, in three stages (3min/stage) of increasing frequency (2Hz, 4Hz, and 6Hz). An Endurance Index (EI) was calculated as the percent of acceleration at the end of each stimulation stage relative to the peak acceleration. Oxygen saturation was measured using near-infrared spectroscopy. Results showed that acceleration correlated with torque during twitch electrical stimulation of the vastus lateralis (mean R 2 = 0.96±0.04; p<0.05). Measures of forearm EI reproducibility were CV= 2.5-7.4%. EI was significantly higher (12.1%) in the gastrocnemius compared to the forearm (p<0.01). Muscle oxygen saturation was not reduced during stimulation of the forearm (72.6±9.8% at 2Hz, 73.2±11.6% at 4Hz, and 71.0±12.5% at 6Hz) compared to resting baseline (74.3±15.1%) (p>0.1). This study found that EI is a reproducible measure of muscle endurance that is not influenced by declines in oxygen saturation. Advances in Skeletal Muscle Function Assessment, Volume 1, Issue 2 15 A recent study has used aMMG to measure the acceleration generated by muscle movement during electrically stimulated muscle twitches in persons with neurological disease [25]. However, the reproducibility and validity of the methodology were not defined. The purpose of the present study was to evaluate the reproducibility and validity of measures of muscle endurance using twitch electrical stimulation and aMMG. We performed four different experiments to: 1) compare twitch acceleration to force measurements , 2) determine the reproducibility of the muscle endurance test at different levels of stimulation current, 3) compare the endurance index of the forearm and calf muscles , and 4) test whether oxygen saturation falls during the endurance index test. We hypothesized that aMMG measures of endurance will be reproducible, not influenced by changes in the level of electrical stimulation current, that the forearm muscles will be more fatigable than the calf, and that twitch electrical stimulation would not lower muscle oxygen levels sufficiently to suggest muscle endurance was limited by oxygen delivery.

Patologie/Applicazioni:

• Stimolazione elettrica transcranica (TES)

Anno:

2017

Tipo di pubblicazione:

Articolo

Parola chiave:

ossigenazione muscolare

Testata scientifica:

ASMFA - Advances in Skeletal Muscle Function Assessment