Effects of various isoresistive training programmes on trunk muscle performance

Effects of aerobic and strength exercise on motor fatigue in men and women with multiple sclerosis: a randomized controlled trial

Objective: To investigate the effects of aerobic and strength exercise on motor fatigue of knee flexor and extensor muscles in subjects with multiple sclerosis (MS).

Design: A randomized controlled trial.

Setting: At Masku Neurological Rehabilitation Centre, Masku, and the Social Insurance Institution, Research Department, Turku, Finland.

Subjects: Ninety-five MS patients with mild to moderate disability were randomized into exercise group (n = 47) and a control group (n = 48).

Intervention: Participants in the exercise group attended in a supervised exercise period of three weeks, which was followed by a home exercise programme lasting for 23 weeks. Patients in the control group continued with their normal living.

Outcome measures: Motor fatigue of knee flexor and extensor muscles was measured during a static 30-s maximal sustained muscle contraction. The decline in force (Nm) during the 30 s was recorded, and a fatigue index (FI) was calculated. Subjective fatigue was measured by using the Fatigue Severity Scale (FSS). The Ambulatory Fatigue Index (AFI) was calculated on the basis of a 500-m walking test. Assessment took place at baseline, at the third week (not for the control group) and at the 26th week. All outcome variables were analysed, men and women together, and some interesting contrasts were analysed by gender.

Results: Associations were observed with changes in extension FI and Expanded Disability Status Scale (EDSS) score and mean extension torque (Nm), but not with changes in FI and aerobic or strength exercise activity, mean AFI, mean FSS or in mean knee flexion torque. AFI was decreased in all subject groups (p = 0.007). Motor fatigue was reduced in knee flexion (p = 0.0014) and extension (ns) among female but not in male exercisers after six months of exercise. The exercise activity of women was 25% higher than that of the men.

Conclusions: Six months of exercise reduced motor fatigue in women, but not in men.

A NORMATIVE DATABASE OF ISOKINETIC UPPER-EXTREMITY JOINT STRENGTHS: TOWARDS THE EVALUATION OF DYNAMIC HUMAN PERFORMANCE

The objective of this study was to provide a normative database of dynamic upper-extremity (shoulder and elbow) joint strengths to fill the current void in literature for multidimensional strength capacity profiles. The isokinetic strength of the elbow and shoulder joints was tested for twenty normal males and females. The independent variables consisted of joint angular position, joint angular velocity, direction of exertion, and gender. The measured joint strength (torque, Nm) was the only defined dependent variable. The majority of existing joint strength prediction models and normative databases are static (isometric) in nature. The few available dynamic models are reported in the form of torque as a function of joint angle. Since joint strength is a function of both the joint angular position and angular velocity, descriptive models should take this interaction into consideration. The dynamic joint strengths of the subjects were studied using the KIN_COM 125E Plus. A second-order multiple regression analysis was used to model the dynamic 3-D strength surface response of each joint in each direction of exertion. Analysis of variance (ANOVA) with repeated measures design was used to test for the effects of gender, angular position, angular velocity, and direction on the dynamic strength of each joint, joint strength was significantly influenced by dynamic parameters such as the angular velocity. The interaction between angular position and velocity was highly significant. 3-D strength surface representation may be used as a "performance capacity envelope" to comprehensively characterize an individual's dynamic joint strength performance.

Isoresistive dynamometer measurement of trunk muscle velocity at different angular phases of flexion and extension

Isoresistive trunk muscle dynamometer is a potentially useful piece of equipment in evaluation of trunk muscle velocity, but to date, studies analysing the possibilities and limitations of such measurements are scarce. The aim of this study was to analyse the trunk muscle velocity in repetitive flexion and extension movements at three different angular phases, using an isoresistive trunk muscle dynamometer, and to assess the reliability of the measurements. The study population consisted of 120 healthy, sedentary men and women who volunteered for the study. The measurements were carried out before and after a 22-week training intervention programme. The results show that the peak velocities of the phases between 15 and 35 degrees in flexion and 20-0 degrees in extension (i.e. the second phases) correlated highly (r=0.99 in flexion and in extension) with the peak velocity of the whole movement ranging from -5 to 55 degrees in flexion and 40 to -20 degrees in extension. Correlations were high, both before and after the intervention. The LISREL model analysis showed high reliability of measurement for the second angular phases (in flexion and extension). According to the model, the correlation between the first and second measurement (with a 22-week training intervention in between) was 0.78 in flexion and 0.81 in extension. In conclusion, the angular phases from 15 to 35 degrees in flexion and from 20 to 0 degrees in extension represent the peak velocity of the whole movement. Negative residual correlations between the first and last angular phases in the LISREL model reflect the way of performing the movement: the faster the start the slower the end, and vice versa.

The effect of fatigue on multijoint kinematics, coordination, and postural stability during a repetitive lifting test

Because of the inability of strength tests to accurately discriminate between low back pain patients and healthy subjects, a multifactorial evaluation of low back pain patients is warranted. It is postulated that measurements of endurance, kinematics, postural stability, and coordination, in addition to strength, are necessary to fully document the patients' functional capabilities. This research study was conducted in order to understand the effects of fatigue on the above factors. Twelve healthy male subjects performed a repetitive lifting test in which a submaximal load was lifted at a maximal rate. Knee, hip, and trunk motion was measured using videography and electrogoniometry, postural stability was measured using a forceplate, and coordination parameters were determined using phase-plane analysis. Fatigue was documented by a 31% reduction in lifting power. At the end of the endurance test, there was less knee and hip range of motion and greater spine peak flexion, while the coordination measures demonstrated that there was greater hip and lumbar spine extension earlier in the lifting phase. The postural stability declined as the test endured. Utilization of these measures may guide physical therapists in their rehabilitation of low back pain patients.