Neural factors versus hypertrophy in the time course of muscle strength gain

Am J Phys Med. 1979 Jun;58(3):115-30.


The time course of strength gain with respect to the contributions of neural factors and hypertrophy was studied in seven young males and eight females during the course of an 8 week regimen of isotonic strength training. The results indicated that neural factors accounted for the larger proportion of the initial strength increment and thereafter both neural factors and hypertrophy took part in the further increase in strength, with hypertrophy becoming the dominant factor after the first 3 to 5 weeks. Our data regarding the untrained contralateral arm flexors provide further support for the concept of cross education. It was suggested that the nature of this cross education effect may entirely rest on the neural factors presumably acting at various levels of the nervous system which could result in increasing the maximal level of muscle activation.

Publication types

  • Comparative Study

MeSH terms

  • Arm / physiology
  • Electric Stimulation
  • Electromyography
  • Female
  • Humans
  • Hypertrophy
  • Isometric Contraction
  • Male
  • Muscle Contraction
  • Muscle Tonus / methods*
  • Muscular Atrophy / therapy
  • Nervous System
  • Physical Therapy Modalities / methods*
  • Time Factors