Deltoid muscle fiber characteristics in adolescent and adult wrestlers.
OBJECTIVE
The aim of the present study was to examine the adaptation of myosin heavy chain (MHC) isoforms, capillary density and fiber cross sectional area (CSA) of deltoid muscle in adolescent and adult elite Greco-Roman wrestlers.


METHODS
Eighteen Greco-Roman wrestlers were divided into two groups: adolescents included 10 athletes (group A) between 14-18 years of age (15.4+/-1.3 yrs) and adults included 8 athletes (group B) between 20-27 years (23.5+/-2.6 yrs). Histochemical analyses were used to determine the muscle fiber type distribution and the muscle fiber cross sectional area. MHC isoform composition was determined with protein electrophoresis, while capillary density (capillary to fiber ratio and capillaries per mm2) analysis was performed with a-amylase Periodic and Schiff staining.


RESULTS
Adolescents demonstrated a significantly higher percentage of type I fibers (P<0.05) and type I fiber area (P<0.05) compared to the adults. The percentage of type IIa fiber area were significantly higher in adult wrestlers (P<0.05). MHC I isoforms was significantly higher in adolescents (P<0.05), whereas the MHC isoforms of IIa and IIx did not differ between groups. The capillary density (mm2) were significantly higher (P<0.05) in adolescents compared to adults.


CONCLUSIONS
Our findings suggest that the observed muscle fiber profile in the deltoid muscle of wrestlers may represent an adaptation based on the mechanical and biochemical demands of the long-term training. Such adaptations are linked to the specific characteristics of the training program, the level and the previous training experience of the wrestlers.
Mandroukas
A
A
Faculty of Physical Education and Sports, Charles University, Prague, Czech Republic. kmandrou@phed.auth.gr
Metaxas
T
T
Kesidis
N
N
Christoulas
K
K
Vamvakoudis
E
E
Stefanidis
P
P
Heller
J
J
Ekblom
B
B
Mandroukas
K
K
D000293:Adolescent; D000328:Adult; D019412:Anatomy, Cross-Sectional; D002196:Capillaries / Q000033:anatomy & histology; D057645:Deltoid Muscle / Q000033:anatomy & histology*; D004586:Electrophoresis; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D013194:Staining and Labeling; D014952:Wrestling; D055815:Young Adult
D020033:Protein Isoforms; D018995:Myosin Heavy Chains