Format

Send to

Choose Destination
Eur J Appl Physiol. 2016 Jan;116(1):49-56. doi: 10.1007/s00421-015-3243-4. Epub 2015 Aug 18.

Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling.

Author information

1
School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello de Morais, 65, São Paulo, SP, 05508-030, Brazil. felipedamas@usp.br.
2
Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
3
School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello de Morais, 65, São Paulo, SP, 05508-030, Brazil.
4
Laboratory of Neuromuscular Adaptations to Resistance Training, Federal University of São Carlos, Rod. Washington Luiz, Km 235-SP310, São Carlos, SP, 13565-905, Brazil.

Abstract

PURPOSE:

It has been proposed that skeletal muscle shows signs of resistance training (RT)-induced muscle hypertrophy much earlier (i.e., ~3-4 weeks of RT) than previously thought. We determined if early increases in whole muscle cross-sectional area (CSA) during a period of RT were concomitant with edematous muscle swelling and thus not completely attributable to hypertrophy.

METHODS:

We analyzed vastus lateralis muscle ultrasound CSA images and their respective echo intensities (CSA-USecho) at the beginning (T1), in the 3rd week of RT (T2) and at the end (T3) of a 10-week RT period in ten untrained young men. Functional parameters [training volume (TV = load × reps × sets) and maximal voluntary contraction (MVC)] and muscle damage markers (myoglobin and interleukin-6) were also assessed.

RESULT:

Muscle CSA increased significantly at T2 (~2.7%) and T3 (~10.4%) versus T1. Similarly, CSA-USecho increased at T2 (~17.2%) and T3 (~13.7%). However, when CSA-USecho was normalized to the increase in muscle CSA, only T2 showed a significantly higher USecho versus T1. Additionally, TV increased at T2 and T3 versus T1, but MVC increased only at T3. Myoglobin and Interleukin-6 were elevated at T2 versus T1, and myoglobin was also higher at T2 versus T3.

CONCLUSION:

We propose that early RT-induced increases in muscle CSA in untrained young individuals are not purely hypertrophy, since there is concomitant edema-induced muscle swelling, probably due to muscle damage, which may account for a large proportion of the increase. Therefore, muscle CSA increases (particularly early in an RT program) should not be labeled as hypertrophy without some concomitant measure of muscle edema/damage.

KEYWORDS:

Echo intensity; Muscle damage; Muscle hypertrophy; Resistance exercise; Skeletal muscle; Ultrasound

PMID:
26280652
DOI:
10.1007/s00421-015-3243-4
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center