Overweight and obese people may have to pump more iron or put in more time at
the gym than their healthy-weight counterparts if they hope to see comparable
gains in muscle strength, according to a new study led by University of Connecticut
The study measured how 449 healthy-weight and 238 overweight or obese men and
women responded to the same 12-week resistance training regimen using their non-dominant
arm. The participants were between the ages of 18 and 39 and had not trained with
weights for at least a year.
The researchers, spread across 10 sites, found that their subjects experienced
comparable increases in muscle size, but not in muscle strength.
“Bigger people have bigger muscles, so you would expect that their response
to resistance training would be greater, but, when we adjusted for weight and evened
the playing field, we found the normal weight group had bigger strength gains,” said
UConn Professor Linda Pescatello, who led the study. “It appears that being
overweight or obese may blunt the beneficial effects of weight training, at least
in the short-term.”
The findings may
be due, in part, to genetic factors that have yet to be identified, said Pescatello,
an associate professor in UConn’s School of Allied Health. An excess of adipose
or fat tissue also may explain the findings as the excess tissue acts as an endocrine
organ, releasing an overabundance of certain hormones that have a negative impact
on muscles, she said.
Pescatello says a longer study using a full-body training regimen is still needed,
but this study, involving the largest number of research subjects to date, has
implications for how strength training exercise might be prescribed for overweight
or obese people.
The recently-concluded study was conducted as part of an ongoing four-year,
multi-site investigation into which genes and genetic variants influence an individual’s
response to resistance training. Funded by a $430,000 grant from the National Institutes
of Health, the overarching research project involves seven other universities as
well as Hartford Hospital and the Research Center for Genetic Medicine at the Children’s
National Medical Center in Washington, D.C.
The other universities involved are: Yale University, University of Central
Florida, University of Massachusetts, West Virginia University, Dublin City University,
Central Michigan University and Florida Atlantic University.
The UConn graduate students who conducted the obesity and weight training
study with Pescatello were Bethany Kelsey, Gary Gianetti and Matthew