The impact of aerobic exercise pre-conditioning to maximize the skeletal muscle adaptive response to resistance type exercise training in healthy older adults

The progressive loss of skeletal muscle mass with aging, or sarcopenia, has a
major impact on our health care system due to increased morbidity and a greater
need for hospitalization and/or institutionalization. Traditional whole-body
resistance exercise is an effective intervention strategy to counter the
detrimental impact of sarcopenia. However, despite its overall beneficial
effects, large heterogeneity exists in the muscle*s adaptive response to
resistance training in older adults. Whereas some individuals show large
increases in muscle mass and strength, others seem to only marginally benefit
from resistance exercise training. It has been suggested that the age-related
reduction skeletal muscle perfusion might be a key limiting factor in the
ability to grow muscle during resistance type exercise training in older
adults. However, little is known whether improving skeletal muscle perfusion,
through aerobic pre-conditioning, could actually augment the beneficial effect
of prolonged resistance exercise training in older adults.

The main objective of this study is to determine the effects of 8 weeks aerobic
exercise pre-conditioning (to improve muscle fiber perfusion capacity) on the
increase in skeletal muscle mass and function during 12 weeks of resistance
exercise training in older adults.

Randomized, controlled intervention study.

Participants will be randomly allocated to perform 8 weeks of aerobic
pre-conditioning (AER) or no exercise control (CON) group. During aerobic
pre-conditioning, participants will perform exercise for 45 minutes at 65-70%
of heart-rate max on a stationary bike or cross-trainer, 3 days per week. The
main aim to the aerobic exercise pre-conditioning period is to improve skeletal
muscle perfusion. Following 8 weeks of pre-conditioning or control, all
participants will engage in a 12-week whole-body resistance exercise training
program, consisting of six different exercises. Leg press, leg extension, chest
press, shoulder press, horizontal row and vertical lateral pull exercise will
be performed on weight lifting machines, 3 days per week. To assess the changes
in response to the different exercise protocols, a series of standardized
measurements will be performed before (pre), after 8 weeks of pre-conditioning
(mid), and following 12 weeks of resistance exercise training (post).

Risks as the result of participation in this experiment are minimal. There are
no complications associated with the procedure of a DXA scan. The level of
radiation emitted during a DXA is merely a fraction of that emitted during a
regular chest X-ray. During this study 20 blood samples and 5 muscle biopsy
samples will be taken. At the site of the blood draw a hematoma could occur.
This is the same for the muscle biopsies. The incision made for obtaining the
muscle biopsy will heal completely. In some cases, the muscle biopsy can be
painful. Infections and bleeding afterwards are possible, but rare. As a result
of the aerobic exercise pre-conditioning and resistance type exercise training
program, participants will likely experience a gain in muscle mass, strength
and a healthy improvement in body composition. Depending on the baseline level
of fitness, this will result in an increase in functional performance. It is
possible that participants may experience muscle soreness induced by
unaccustomed exercise.