European Journal of Applied Physiology and Occupational Physiology

, Volume 59, Issue 4, pp 310–319

Changes in force, cross-sectional area and neural activation during strength training and detraining of the human quadriceps


  • M. V. Narici
    • Reparto Fisiologia Lavoro MuscolareI.T.B.A. C.N.R.
  • G. S. Roi
    • Reparto Fisiologia Lavoro MuscolareI.T.B.A. C.N.R.
  • L. Landoni
    • Servizio di RMN, Centro S. Pio X
  • A. E. Minetti
    • Reparto Fisiologia Lavoro MuscolareI.T.B.A. C.N.R.
  • P. Cerretelli
    • Reparto Fisiologia Lavoro MuscolareI.T.B.A. C.N.R.

DOI: 10.1007/BF02388334

Cite this article as:
Narici, M.V., Roi, G.S., Landoni, L. et al. Europ. J. Appl. Physiol. (1989) 59: 310. doi:10.1007/BF02388334


Four male subjects aged 23–34 years were studied during 60 days of unilateral strength training and 40 days of detraining. Training was carried out four times a week and consisted of six series of ten maximal isokinetic knee extensions at an angular velocity of 2.09 rad·s−1. At the start and at every 20th day of training and detraining, isometric maximal voluntary contraction (MVC), integrated electromyographic activity (iEMG) and quadriceps muscle cross-sectional area (CSA) assessed at seven fractions of femur length (Lf), by nuclear magnetic resonance imaging, were measured on both trained (T) and untrained (UT) legs. Isokinetic torques at 30° before full knee extension were measured before and at the end of training at: 0, 1.05, 2.09, 3.14, 4.19, 5.24 rad·s−1. After 60 days T leg CSA had increased by 8.5%±1.4% (mean±SEM,n=4,p<0.001), iEMG by 42.4%±16.5% (p<0.01) and MVC by 20.8%±5.4% (p<0.01). Changes during detraining had a similar time course to those of training. No changes in UT leg CSA were observed while iEMG and MVC increased by 24.8%±10% (N.S.) and 8.7%±4.3% (N.S.), respectively. The increase in quadriceps muscle CSA was maximal at 2/10 Lf (12.0%±1.5%,p<0.01) and minimal, proximally to the knee, at 8/10 Lf (3.5%±1.2%, N.S.). Preferential hypertrophy of the vastus medialis and intermedius muscles compared to those of the rectus femoris and lateralis muscles was observed. Isoangular torque of T leg increased by 20.9%±5.4% (p<0.05), 23.8%±7.8% (p<0.05) and 22.5%±6.7% (p<0.05) at 0, 1.05 and 2.09 rad·s−1 respectively; no significant change was observed at higher velocities and in the UT leg. Hypertrophy produced by strength training accounts for 40% of the increase in force while the remaining 60% seems to be attributable to an increased neural drive and possibly to changes in muscle architecture.

Key words

Strength training/detrainingHypertrophyEMGNuclear magnetic resonance imaging

Copyright information

© Springer-Verlag 1989