Skeletal muscle fat oxidation is increased in African-American and white women after 10 days of endurance exercise training.
OBJECTIVE
Obesity is associated with lower rates of skeletal muscle fatty acid oxidation (FAO), which is linked to insulin resistance. FAO is reduced further in obese African-American (AAW) vs. white women (CW) and may also be lower in lean AAW vs. CW. In lean CW, endurance exercise training (EET) elevates the oxidative capacity of skeletal muscle. Therefore, we determined whether EET would elevate skeletal muscle FAO similarly in AAW and CW with a lower lipid oxidative capacity.


METHODS
In vitro rates of FAO were assessed in rectus abdominus muscle strips using [1- 14C] palmitate (Pal) from lean AAW [BMI = 24.2 +/- 0.9 (standard error) kg/m2] and CW (23.6 +/- 0.8 kg/m2) undergoing voluntary abdominal surgery. Lean AAW (22 +/- 0.9 kg/m(2)) and CW (24 +/- 0.8 kg/m2) and obese AAW (36 +/- 1.2 kg/m2) and CW (40 +/- 1.3 kg/m2) underwent 10 consecutive days of EET on a cycle ergometer (60 min/d, 75% peak oxygen uptake). FAO was measured in vastus lateralis homogenates as captured 14CO2 using [1- 14C] Pal, palmitoyl-CoA (Pal-CoA), and palmityl-carnitine (Pal-Car).


RESULTS
Muscle strip experiments showed suppressed rates of FAO (p = 0.03) in lean AAW vs. CW. EET increased the rates of skeletal muscle Pal oxidation (p = 0.05) in both lean AAW and CW. In obese subjects, Pre-EET Pal (but not Pal-CoA or Pal-Car) oxidation was lower (p = 0.05) in AAW vs. CW. EET increased Pal oxidation 100% in obese AAW (p < 0.05) and 59% (p < 0.05) in obese CW. Similar increases (p < 0.05) in post-EET FAO were observed for Pal-CoA and Pal-Car in both groups.


CONCLUSIONS
Both lean and obese AAW possess a lower capacity for skeletal muscle FAO, but EET increases FAO similarly in both AAW and CW. These data suggest the use of EET for treatment against obesity and diabetes for both AAW and CW.
Cortright
Ronald N
RN
The Human Performance Laboratory, Department of Excercise and Sport Science, College of Health and Human Performance, The Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA. cortrightr@ecu.edu
Sandhoff
Kimberly M
KM
Basilio
Jessica L
JL
Berggren
Jason R
JR
Hickner
Robert C
RC
Hulver
Matthew W
MW
Dohm
G Lynis
GL
Houmard
Joseph A
JA
D000328:Adult; D001741:Black or African American; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D006801:Humans; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000208:ethnology* / Q000378:metabolism* / Q000517:prevention & control; D010084:Oxidation-Reduction; D019308:Palmitic Acid / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010172:Palmitoylcarnitine / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology*; D046509:Tissue Culture Techniques; D044465:White People
D005227:Fatty Acids; D010171:Palmitoyl Coenzyme A; D010172:Palmitoylcarnitine; D019308:Palmitic Acid; D002950:Citrate (si)-Synthase; D003066:Coenzyme A Ligases