The purpose of this study was to examine if the regional difference in muscle hypertrophy after chronic resistance training is associated with muscle activation after one session of resistance exercise. Twelve men performed one session of resistance exercise of elbow extensors. Before and immediately after the exercise, transverse relaxation time (T2)-weighted magnetic resonance (MR) images of upper arm were recorded to evaluate the muscle activation along its length. In the MR images, T2 for the pixels within the triceps brachii muscle was quantified. The number of pixels with T2 greater than the threshold (mean + 1SD of T2 before the exercise) was expressed as the ratio to the number of pixels occupied by the muscle (%activated area). Another 12 subjects completed 12 weeks of training intervention (3 days per week), which consisted of the same program variables as used in the experiment for the T2 measurement. The cross-sectional areas of the triceps brachii before and after the training intervention were measured from MR images of upper arm. The %activated area of the triceps brachii induced by one session of the exercise was found to be significantly lower in the distal region than the middle and proximal regions. Similarly, the relative increase in muscle cross-sectional area after the 12 weeks of training intervention was significantly less in the distal region than the middle and proximal regions. The results suggest that the regional difference in muscle hypertrophy after chronic resistance training is attributable to the regional difference in muscle activation during the exercise.
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Aagaard P, Andersen JL, Dyhre-Poulsen P, Leffers AM, Wagner A, Magnusson SP, Halkjaer-Kristensen J, Simonsen EB (2001) A mechanism for increased contractile strength of human pennate muscle in response to strength training: changes in muscle architecture. J Physiol 534:613–623
Adams GR, Duvoisin MR, Dudley GA (1992) Magnetic resonance imaging and electromyography as indexes of muscle function. J Appl Physiol 73:1578–1583
Adams GR, Harris RT, Woodard D, Dudley GA (1993) Mapping of electrical muscle stimulation using MRI. J Appl Physiol 74:532–537
Akima H, Takahashi H, Kuno SY, Katsuta S (2004) Coactivation pattern in human quadriceps during isokinetic knee-extension by muscle functional MRI. Eur J Appl Physiol 91:7–14
Blazevich AJ, Cannavan D, Coleman DR, Horne S (2007) Influence of concentric and eccentric resistance training on architectural adaptation in human quadriceps muscles. J Appl Physiol 103:1565–1575
Buchanan TS, Almdale DP, Lewis JL, Rymer WZ (1986) Characteristics of synergic relations during isometric contractions of human elbow muscles. J Neurophysiol 56:1225–1241
Elder GC, Bradbury K, Roberts R (1982) Variability of fiber type distributions within human muscles. J Appl Physiol 53:1473–1480
Fisher MJ, Meyer RA, Adams GR, Foley JM, Potchen EJ (1990) Direct relationship between proton T2 and exercise intensity in skeletal muscle MR images. Invest Radiol 25:480–485
Fleckenstein JL, Bertocci LA, Nunnally RL, Parkey RW, Peshock RM (1989) Exercise-enhanced MR imaging of variations in forearm muscle anatomy and use: importance in MR spectroscopy. AJR Am J Roentgenol 153:693–698
Giordano SB, Segal RL (2006) Leg muscles differ in spatial activation patterns with differing levels of voluntary plantarflexion activity in humans. Cells Tissues Organs 184:42–51
Harber MP, Fry AC, Rubin MR, Smith JC, Weiss LW (2004) Skeletal muscle and hormonal adaptations to circuit weight training in untrained men. Scand J Med Sci Sports 14:176–185
Housh DJ, Housh TJ, Johnson GO, Chu WK (1992) Hypertrophic response to unilateral concentric isokinetic resistance training. J Appl Physiol 73:65–70
Kanehisa H, Nagareda H, Kawakami Y, Akima H, Masani K, Kouzaki M, Fukunaga T (2002) Effects of equivolume isometric training programs comprising medium or high resistance on muscle size and strength. Eur J Appl Physiol 87:112–119
Kawakami Y, Abe T, Kuno SY, Fukunaga T (1995) Training-induced changes in muscle architecture and specific tension. Eur J Appl Physiol Occup Physiol 72:37–43
Kawakami Y, Abe T, Kanehisa H, Fukunaga T (2006) Human skeletal muscle size and architecture: variability and interdependence. Am J Hum Biol 18:845–848
Kinugasa R, Kawakami Y, Fukunaga T (2005) Muscle activation and its distribution within human triceps surae muscles. J Appl Physiol 99:1149–1156
Kuno S, Katsuta S, Akisada M, Anno I, Matsumoto K (1990) Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition. Eur J Appl Physiol Occup Physiol 61:33–36
MacDougall JD, Elder GC, Sale DG, Moroz JR, Sutton JR (1980) Effects of strength training and immobilization on human muscle fibres. Eur J Appl Physiol Occup Physiol 43:25–34
Melnyk JA, Rogers MA, Hurley BF (2009) Effects of strength training and detraining on regional muscle in young and older men and women. Eur J Appl Physiol 105:929–938
Narici MV, Roi GS, Landoni L, Minetti AE, Cerretelli P (1989) Changes in force, cross-sectional area and neural activation during strength training and detraining of the human quadriceps. Eur J Appl Physiol Occup Physiol 59:310–319
Narici MV, Hoppeler H, Kayser B, Landoni L, Claassen H, Gavardi C, Conti M, Cerretelli P (1996) Human quadriceps cross-sectional area, torque and neural activation during 6 months strength training. Acta Physiol Scand 157:175–186
Prior BM, Ploutz-Snyder LL, Cooper TG, Meyer RA (2001) Fiber type and metabolic dependence of T2 increases in stimulated rat muscles. J Appl Physiol 90:615–623
Roman WJ, Fleckenstein J, Stray-Gundersen J, Alway SE, Peshock R, Gonyea WJ (1993) Adaptations in the elbow flexors of elderly males after heavy-resistance training. J Appl Physiol 74:750–754
Segal RL, Song AW (2005) Nonuniform activity of human calf muscles during an exercise task. Arch Phys Med Rehabil 86:2013–2017
Segal RL, Wolf SL, DeCamp MJ, Chopp MT, English AW (1991) Anatomical partitioning of three multiarticular human muscles. Acta Anat (Basel) 142:261–266
Seynnes OR, de Boer M, Narici MV (2007) Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training. J Appl Physiol 102:368–373
Shellock FG, Fukunaga T, Mink JH, Edgerton VR (1991) Acute effects of exercise on MR imaging of skeletal muscle: concentric vs eccentric actions. AJR Am J Roentgenol 156:765–768
Smith RC, Rutherford OM (1995) The role of metabolites in strength training. I. A comparison of eccentric and concentric contractions. Eur J Appl Physiol Occup Physiol 71:332–336
Tracy BL, Ivey FM, Hurlbut D, Martel GF, Lemmer JT, Siegel EL, Metter EJ, Fozard JL, Fleg JL, Hurley BF (1999) Muscle quality. II. Effects of strength training in 65- to 75-yr-old men and women. J Appl Physiol 86:195–201
Wakahara T, Takeshita K, Kato E, Miyatani M, Tanaka NI, Kanehisa H, Kawakami Y, Fukunaga T (2010) Variability of limb muscle size in young men. Am J Hum Biol 22:55–59
Yue G, Alexander AL, Laidlaw DH, Gmitro AF, Unger EC, Enoka RM (1994) Sensitivity of muscle proton spin–spin relaxation time as an index of muscle activation. J Appl Physiol 77:84–92
This work was supported by Grant-in-Aid for Young Scientists (B, 21700630). The authors gratefully acknowledge Dr. Ryuta Kinugasa for technical support for T2 measurement.
Conflict of interest
None of the authors have a conflict of interest.
Communicated by William J. Kraemer.
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Wakahara, T., Miyamoto, N., Sugisaki, N. et al. Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training. Eur J Appl Physiol 112, 1569–1576 (2012). https://doi.org/10.1007/s00421-011-2121-y
- Transverse relaxation time
- Magnetic resonance image
- Cross-sectional area
- Triceps brachii muscle