Jc. Agre et al., STRENGTH, ENDURANCE, AND WORK CAPACITY AFTER MUSCLE STRENGTHENING EXERCISE IN POSTPOLIO SUBJECTS, Archives of physical medicine and rehabilitation, 78(7), 1997, pp. 681-686
Objective: To determine whether a 12-week home quadriceps muscle stren
gthening exercise program would increase muscle strength, isometric en
durance, and tension time index (TTI) in postpolio syndrome subjects w
ithout adversely affecting the surviving motor units or the muscle. De
sign: A longitudinal study to investigate the effect of a 12-week exer
cise program on neuromuscular function and electromyographic variables
. Setting: Neuromuscular laboratory of a university hospital. Subjects
: Seven subjects were recruited from a cohort of 12 subjects who had p
articipated in a previous exercise study. All subjects had greater tha
n antigravity strength of the quadriceps. Upon completion of a postpol
io questionnaire, all acknowledged common postpolio syndrome symptoms
such as new fatigue, pain, and weakness; 6 of the 7 acknowledged new s
trength decline. Intervention: On Mondays and Thursdays subjects perfo
rmed three sets of four maximal isometric contractions of the quadrice
ps held for 5 seconds each. On Tuesdays and Fridays subjects performed
three sets of 12 dynamic knee extension exercises with ankle weights.
Main Outcome Measures: Neuromuscular variables of the quadriceps musc
les were measured at the beginning and completion of the exercise prog
ram and included: isokinetic peak torque (ISOKPT, at 60 degrees/sec an
gular velocity) and total work performed of four contractions (ISOKTW)
, Isometric peak torque (MVC), endurance (EDUR, time subject could hol
d isometric contraction at 40% of the initial MVC), isometric tension
time index (TTI, product of endurance time and torque at 40% of MVC),
and initial and final ankle weight (WGT, kg) lifted. Electromyographic
variables included: fiber density (FD), jitter (MCD), and blocking (B
LK) from single fiber assessment and median macro amplitude (MACRO). S
erum creatine kinase (CK) was also measured initially and at 4-week in
tervals throughout the study. Results: The following variables signifi
cantly (p < .05) increased: WGT by 47%, ISOKPT, 15%, ISOKTW, 15%; MVC,
36%; EDUR, 21%; TTI, 18%. The following variables did not significant
ly (p > .05) change: FD, MCD, BLK, MACRO, and CK. Conclusions: This ho
me exercise program significantly increased strength, endurance, and T
TI without apparently adversely affecting the motor units or the muscl
e, as the EMG and CK variables did not change. (C) 1997 by the America
n Congress of Rehabilitation Medicine and the American Academy of Phys
ical Medicine and Rehabilitation.