A weekly bout of eccentric exercise is sufficient to induce health-promoting effects.
OBJECTIVE
The effects of chronic eccentric-only versus concentric-only exercise on muscle physiology and blood biochemistry were investigated.


METHODS
Twenty women performed on an isokinetic dynamometer a concentric (n = 10;mean ± SEM: age = 21.0 ± 0.4 yr, body fat = 22.0% ± 0.9%) or an eccentric (n = 10, age = 20.0 ± 0.3 yr, body fat = 23.2% ± 0.7%) exercise session using the knee extensors of both lower limbs once a week for eight subsequent weeks. Muscle function (isometric, concentric, and eccentric peak torque, range of movement, and soreness) was evaluated before, immediately after, and 48 h postexercise in each one of the eight training weeks. Body fat, resting energy expenditure (REE), lipid, and carbohydrate oxidation rate as well as blood chemistry measurements (lipid, lipoprotein and apolipoprotein profile, glucose, insulin, glycosylated hemoglobin, and creatine kinase) were examined before and 48 h postexercise at the first and eighth week of training.


RESULTS
Acute eccentric exercise increased REE and fat oxidation at week 1 (12.7% and 12.9%, respectively) and at week 8 (0.7% and 2.8%, respectively). Chronic eccentric exercise increased resting REE and fat oxidation at week 8 compared with week 1 (5.0% and 9.9%, respectively). Acute eccentric exercise improved blood lipid profile at week 1 and week 8. Chronic eccentric exercise improved resting blood lipid profile at week 8. Acute eccentric exercise increased insulin resistance at week 1 but not at week 8. Chronic eccentric exercise decreased resting insulin resistance at week 8.


CONCLUSIONS
It is reported for the first time that only 30 min of eccentric exercise per week for 8 wk was sufficient to improve health risk factors.
Paschalis
Vassilis
V
Institute of Human Performance and Rehabilitation, Center for Research and Technology-Thessaly, Trikala, Greece.
Nikolaidis
Michalis G
MG
Theodorou
Anastasios A
AA
Panayiotou
George
G
Fatouros
Ioannis G
IG
Koutedakis
Yiannis
Y
Jamurtas
Athanasios Z
AZ
D050260:Carbohydrate Metabolism / Q000502:physiology; D002784:Cholesterol / Q000097:blood; D015930:Diet Records; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008066:Lipolysis / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
D014280:Triglycerides; D002784:Cholesterol