Strength, endurance, and work capacity after muscle strengthening exercise in postpolio subjects.
OBJECTIVE
To determine whether a 12-week home quadriceps muscle strengthening exercise program would increase muscle strength, isometric endurance, and tension time index (TTI) in postpolio syndrome subjects without adversely affecting the surviving motor units or the muscle.


METHODS
A longitudinal study to investigate the effect of a 12-week exercise program on neuromuscular function and electromyographic variables.


METHODS
Neuromuscular laboratory of a university hospital.


METHODS
Seven subjects were recruited from a cohort of 12 subjects who had participated in a previous exercise study. All subjects had greater than antigravity strength of the quadriceps. Upon completion of a postpolio questionnaire, all acknowledged common postpolio syndrome symptoms such as new fatigue, pain, and weakness; 6 of the 7 acknowledged new strength decline.


METHODS
On Mondays and Thursdays subjects performed three sets of four maximal isometric contractions of the quadriceps held for 5 seconds each. On Tuesdays and Fridays subjects performed three sets of 12 dynamic knee extension exercises with ankle weights.


METHODS
Neuromuscular variables of the quadriceps muscles were measured at the beginning and completion of the exercise program and included: isokinetic peak torque (ISOKPT, at 60 degrees/sec angular velocity) and total work performed of four contractions (ISOKTW), isometric peak torque (MVC), endurance (EDUR, time subject could hold 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 (BLK) from single fiber assessment and median macro amplitude (MACRO). Serum creatine kinase (CK) was also measured initially and at 4-week intervals throughout the study.


RESULTS
The following variables significantly (p < .05) increased: WGT by 47%, ISOKPT, 15%, ISOKTW, 15%; MVC, 36%; EDUR, 21%; TTI, 18%. The following variables did not significantly (p > .05) change: FD, MCD, BLK, MACRO, and CK.


CONCLUSIONS
This home exercise program significantly increased strength, endurance, and TTI without apparently adversely affecting the motor units or the muscle, as the EMG and CK variables did not change.
Agre
J C
JC
Department of Rehabilitation Medicine, University of Wisconsin Medical School, Madison, USA.
Rodriquez
A A
AA
Franke
T M
TM
D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D004576:Electromyography; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D007537:Isometric Contraction; D008137:Longitudinal Studies; D008875:Middle Aged; D010807:Physical Endurance; D016262:Postpoliomyelitis Syndrome / Q000097:blood / Q000503:physiopathology / Q000534:rehabilitation*; D016896:Treatment Outcome; D014891:Weight Lifting; D014938:Work Capacity Evaluation
D003402:Creatine Kinase