X hits on this document

PDF document

Mechanical overload and skeletal muscle fiber hyperplasia: a meta-analysis - page 4 / 6

25 views

0 shares

0 downloads

0 comments

4 / 6

1586

OVERLOAD AND HYPERPLASIA

Fig. 1. Percent changes in skeletal muscle mass (n 5 37), fiber area

(n 5 25), and fiber number (n 5 37).

, Outliers beyond 10th and 90th

percentiles. treatment

Percent 100.

change

calculated

as

(treatment

2

control)/

Fig. 3. Percent increases in muscle fiber number according to

whether species was change calculated as

avian (n 5 20) or mammalian (n (treatment 2 control)/treatment

5 17). 100.

Percent

sum test. Differences between changes in muscle fiber num- ber partitioned according to potentially confounding vari- ables (fiber-counting technique, species used, fiber arrangement of muscles, and type of control) were also examined by using Mann-Whitney rank-sum tests. A one-way analysis of variance test (Kruskal-Wallis) was used to exam- ine the effect of different types of mechanical overload (stretch, exercise, and compensatory hypertrophy) on muscle fiber number. All data were reported as means 6 SD. The significance level was set at P # 0.05.

RESULTS

Literature search. A total of 17 studies yielding 37 data points (some studies had .1 group) and 360

subjects met the initial criteria for inclusion (1–7, 9, 15–19, 21, 28, 30–31). Two quantitative studies (27, 33) were excluded because of insufficient information needed to accurately calculate percent changes in muscle fiber number. Another eight studies (10–11, 13, 22–25, 32) were excluded because only qualitative information was provided on muscle fiber number.

Study characteristics. A summary of study character- istics is given in Table 1. More studies ( 53%) used chronic or intermittent stretch vs. exercise or compen- satory hypertrophy (ablation, tenotomy) as the form of mechanical overload. Approximately 47% of the studies

used the quail to examine

while

53%

examined

the

muscle fiber hyperplasia anterior latissimus dorsi

Fig. 2. Percent increases in muscle fiber number according to whether histological (Histo; n 5 15) or nitric acid digestion (n 5 22) method was used. Percent change calculated as (treatment2 control)/

Fig. 4. Percent increases in muscle fiber number according to whether mechanical overload consisted of stretch (n 5 20), compensa-

tory hypertrophy (CH; n 5 10), or exercise (n5 7). Percent

change

treatment

100.

calculated as (treatment 2 control)/treatment

100.

Downloaded from on December 30, 2014

Document info
Document views25
Page views29
Page last viewedFri Oct 28 06:51:47 UTC 2016
Pages6
Paragraphs222
Words4122

Comments