Muscle activation and perceived loading during rehabilitation exercises: comparison of dumbbells and elastic resistance.
BACKGROUND
High-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be examined.


OBJECTIVE
The aim of this study was to investigate muscle activation and perceived loading during upper-extremity resistance exercises with dumbbells compared with elastic tubing.


METHODS
A single-group, repeated-measures study design was used.


METHODS
Exercise evaluation was conducted in a laboratory setting.


METHODS
Sixteen female workers (aged 26-55 years) without serious musculoskeletal diseases and with a mean neck and shoulder pain intensity of 7.8 on a 100-mm visual analog scale participated in the study.


METHODS
Electromyographic (EMG) activity was measured in 5 selected muscles during the exercises of lateral raise, wrist extension, and shoulder external rotation during graded loadings with dumbbells (2-7.5 kg) and elastic tubing (Thera-Band, red to silver resistance). The order of exercises and loadings was randomized for each individual. Electromyographic amplitude was normalized to the absolute maximum EMG amplitude obtained during maximal voluntary isometric contraction and exercise testing. Immediately after each set of exercise, the Borg CR10 scale was used to rate perceived loading during the exercise.


RESULTS
Resistance exercise with dumbbells as well as elastic tubing showed increasing EMG amplitude and perceived loading with increasing resistance. At the individually maximal level of resistance for each exercise-defined as the 3 repetitions maximum-normalized EMG activity of the prime muscles was not significantly different between dumbbells (59%-87%) and elastic tubing (64%-86%). Perceived loading was moderately to very strongly related to normalized EMG activity (r=.59-.92). Limitations The results of this study apply only for exercises performed in a controlled manner (ie, without sudden jerks or high acceleration).


CONCLUSIONS
Comparably high levels of muscle activation were obtained during resistance exercises with dumbbells and elastic tubing, indicating that therapists can choose either type in clinical practice. The Borg CR10 can be a useful aid in estimating intensity of individual rehabilitation protocols.
National Research Centre for the Working Environment, Lersø Parkalle 105, DK 2100 Copenhagen, Denmark. LLA@NRCWE.DK
Lars L
LL
Andersen
Christoffer H
CH
Andersen
Ole S
OS
Mortensen
Otto M
OM
Poulsen
Inger Birthe T
IB
Bjørnlund
Mette K
MK
Zebis
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training / Q000295:instrumentation*; D034941:Upper Extremity / Q000502:physiology*