Affiliations: [a] Department of Physical Therapy, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil | [b] Exercise Research Laboratory, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil | [c] Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, AB, Canada
Correspondence:
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Corresponding author: Bruno Manfredini Baroni, Exercise Research Laboratory, Felizardo St., 750, Porto Alegre, RS 90690-200, Brazil. Tel.: +55 51 33085860; Fax: +55 51 33085858; E-mail:bmbaroni@yahoo.com.br
Abstract: PURPOSE: This review is aimed at describing the methods used in
knee extensor eccentric resistance training in healthy subjects and at
evaluating the adaptations in strength, activation and structure of this
muscle group. METHODS: Seventy-five studies were carefully analyzed and 30 are
considered in this review. RESULTS: Training programs comprised of 1-4 sessions per week for a
period ranging from four to 20 weeks with isokinetic dynamometers or
conventional strength training machines were considered. Isokinetic
eccentric training programs included 1-6 sets of 6-12 repetitions, while
isotonic eccentric training programs consisted of 3-7 sets of 5-10
repetitions. Eccentric strength gains per training session (0.45-3.42%)
were typically found to be greater compared to isometric (0.08-1.30%) and
concentric (0.23-1.44%) strength gains. Quadriceps activation was
improved in tests performed eccentrically and isometrically, but there is
poor evidence of increased concentric activation and reduced co-activation
of antagonistic muscles. Regarding muscle structure, significant
hypertrophic responses have been demonstrated through increases in
anatomical/physiological cross-sectional area, muscle thickness and fiber
diameter. Most studies measuring muscle architectural changes reported
increased fascicle lengths without changes in pennation angle. Adaptations
in fiber type distribution were inconsistent. CONCLUSIONS: Strength gains following knee extensor eccentric
training are caused by neural and structural adaptations, and may contribute
to physical fitness in healthy populations and health improvement in
patients.
