Greater initial adaptations to submaximal muscle lengthening than maximal shortening.
The purpose of this study was to compare the short-term strength and neural adaptations to eccentric and concentric training at equal force levels. Forty-two sedentary women (age = 21.5 yr) were ranked based on the initial quadriceps strength score, and trios of subjects were randomly assigned to either an eccentric (n = 14), a concentric (n = 14), or a nonexercising control group (n = 14). Training involved a total of 824 eccentric or concentric quadriceps actions at 1.05 rad.s-1 administered in four sets of 6-10 repetitions, four times per week for 6 wk. Before and after training, all subjects were tested for unilateral maximal isometric and eccentric and concentric actions at 1.05 rad.s-1 and for a 40-repetition eccentric and concentric fatigue series of the left and right quadriceps. Surface electromyographic activity of the vastus lateralis and medialis was monitored during testing. Concentric training increased concentric (36%, P < 0.05), isometric (18%, P < 0.05), and eccentric strength (13%), and eccentric training increased eccentric (42%, P < 0.05), isometric (30%, P < 0.05), and concentric (13%) strength. Eccentric training improved eccentric and isometric strength more (P < 0.05) than did concentric training. The electromyographic adaptations were greater with eccentric training. Cross-education was 6%, and neither training mode modified fatigability. The data suggest that training of the quadriceps muscle with submaximal eccentric actions brings about greater strength adaptations faster than does training with maximal-level concentric actions in women. This greater adaptation is likely to be mediated by both mechanical and neural factors.
Biomechanics Laboratory, East Carolina University, Greenville, North Carolina 27858, USA. hphortob@ecuvm.cis.ecu.edu
T
T
Hortobágyi
J
J
Barrier
D
D
Beard
J
J
Braspennincx
P
P
Koens
P
P
Devita
L
L
Dempsey
J
J
Lambert
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D004576:Electromyography; D015444:Exercise; D005260:Female; D006801:Humans; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010809:Physical Fitness