Assessment of a novel strategy to attenuate muscle mass loss during 2 weeks of bed rest

Various cases of injury or illness require hospitalization. Due to the physical
inactivity (or muscle disuse) that is associated with this hospitalization,
individuals lose muscle mass and strength. The more muscle mass and strength is
lost, the longer it takes to recover from this period of hospitalization. Hence
it is of utmost importance to minimize the loss of skeletal muscle mass and
strength during prolonged periods of inactivity such as bed rest. A potential
strategy to attenuate skeletal muscle mass and strength loss during bed rest is
the application of blood flow restriction. This means that, by the temporary
inflation of a cuff around the leg, the blood flow to the muscle will be
restricted. However, it remains to be elucidated whether this method indeed
prevents/attenuates muscle mass and strength loss.

In this study we will assess whether the application of daily blood flow
restriction during 2 weeks of bed rest will attenuate losses in skeletal muscle
mass and strength. With measurements, before, during and after the bed rest
period, we can assess the impact of blood flow restriction during inactivity.

A controlled "within-subjects" design.

Applying blood flow restriction during 2 weeks of bed rest.

There are not many risks involved in this study. The insertion of the catheter
and/or venipuncture for blood draws from a vein in the arm/hand during the
different test days may lead to a small, local hematoma. This also applies for
the possibility of a hematoma at the biopsy site. The incision made at the
biopsy site will close up within two days. The muscle will recover from the
biopsy without permanent effects.
Since it is not allowed to perform any weight-bearing activities, the risk for
deep vein thrombosis (DVT) is increased. To minimize the risk of DVT,
participants are requested to perform an exercise routine which will help to
minimize the risk of developing thrombosis three times per day during the
bed-rest period. Every small surgical procedure, as well as for instance a
venipuncture (blood sample) and a muscle and fat biopsy, can be slightly
painful in some cases. In some exceptional cases, taking a muscle biopsy is
painful. Hematoma*s, infections etc. are possible but extremely rare. The
muscle and fat biopsies will be taken by an experienced physician. Before and
immediately after the bed-rest period DEXA- and CT-scans will be performed. The
radiation released during the DEXA- and CT-scan in this study will be lower
than the background radiation in the Netherlands, which is 2.5 mSV per years,
and will cause no risks. MRI has no radiation involved and will also have no
risks. However, it is important that participants are not wearing any metals
inside and/or outside of your body (e.g., pacemakers, chains, rings etc.) as
this might be attracted to the magnet of the MRI device. The labelled water
that will be used in this study has been used extensively in previous research
studies and there are no risks involved. One possible, but unlikely, event that
might be a result of ingestion of the labelled water is that participants might
experience some feelings of dizziness for a short period of time directly after
ingestion. However, this is very unlikely in the small dosages that we provide.
Finally, it is important to realize that as a consequence of the 14 day bed
rest period participants are likely to experience a reduction in muscle mass
and strength. Due to the reduction in muscle mass and strength participants are
also likely to experience some degree of reduced coordination and/or balance
for the first day or two following bed rest. Previous research shows that in
only a few weeks, muscle mass, strength and coordination/balance is fully
restored.