Increased training load in athletes

Overtraining is a serious problem in the athlete*s world. *Overtraining is an
accumulation of training and/or non-training stress resulting in long-term
decrement in performance capacity with or without related physiological and
psychological signs and symptoms of overtraining in which restoration of
performance capacity may take several weeks or months*. (ECSS joint consensus
statement on the definition of overtraining Meeusen et al 2013).
Estimating prevalence of overtraining is difficult, but it happens to
approximately 30 to 60% of all athletes at one point in his/her athletic
career. Sport physicians need to assess a combination of symptoms and exclude a
list of diseases to finally diagnose an athlete as being overtrained. Of
course, by that time, harm has been done, and the athlete faces a long time of
recovery and underperformance. Therefore, early detection of signals of
overload that could lead to overtraining, has high priority in sport research.
A solution would be to monitor athletes during their training program to follow
certain markers that suggest a risk of overtraining in an early stage. Early
*markers* that were studied in the past are heart rate (variability), hormones,
psychological symptoms (Profile of mood states (POMS) questionnaire) and
C-reactive protein. The results of these studies are divergent and an effective
way of monitoring is still lacking.
As inflammatory markers (cytokines), like interleukins, can explain many of the
symptoms of overtraining, (see also reference Smith et al 2004 *Tissue trauma:
the underlying cause of overtraining syndrome?*) we want to assess, in a future
study, whether these cytokines are indeed a good *early marker*.
Research to find these early markers for overtraining is done by assigning
athletes to an increased training load. Training load is extended in a
controlled fashion, to cause underperformance. As described in the definition:
underperformance is the only central criteria for overtraining.
In past research, various strategies were used to extend the normal training
program of an athlete. An effective strategy among runners was used by Lehmann.
In this strategy, both training volume and intensity increased in 4 weeks* time
from 100% till 200% and from 100% till 130%, respectively.
Lehmann considered endurance runners and runners in this study, while we will
consider a different type of sport: cycling, and include triathletes and
cyclists. This is for practical reasons, as we don*t have equipment available
to measure running performance (we have a bicycle ergometer only). Moreover,
cycling is the preferred exercise mode to do experimental research, as it can
easier be combined with other measures, e.g. sampling of blood or monitoring
oxygen consumption is much more convenient while cycling instead of running.
Finally increasing running load could easier result in physical injuries due to
high impact of running on low extremities, this risk is much lower in cyclists.
Before we use this training protocol in a more extensive study to monitor
changes in cytokine profiles during increased training load, we should test
whether this protocol also leads to underperformance in a controlled and safe
way in our setting (with triathletes and cyclist instead of runners).
Therefore, the aim of this study is to test whether a 4 week training protocol
with a gradual increase in both volume and intensity (from now on we will call
this the adapted training protocol) leads to underperformance. Performance will
be measured with a simulated time trial on a bicycle ergometer, a well-accepted
method to measure performance. When the adapted training protocol leads to
underperformance (>2% increase in time), we will use that protocol in a future
study in which we will assess changes in specific markers, i.e. cytokines.

The main objective of this study is to test whether the adapted training
protocol induces underperformance (>2% increase in time) in trained cyclists
and triathletes.

A training intervention of 4 weeks, in which training load increases. Time
trials are performed directly before and after this training period.
Follow-up/After-care: after the adapted training period, a recovery period (2
weeks) follows, hereafter another time trial is performed.

The intervention consists of a 4 week training period with increased volume and
increased intensity (volume increases from 100% to 200% in 4 weeks, intensity
increases from 100% to 130% in 4 weeks). Logbooks are filled in during this
period. Training data (heart rate, distance, duration) will be monitored using
watches and GPS. Participants will be tested prior to this period and after
this period with time trials. These tests are simulated 10km time trials on a
bicycle ergometer. Before the time trial they fill out a POMS questionnaire and
after the time trial they will grade the exercise intensity on a Borg scale.

Each participant has to visit the University five times (one time for
information, 1 time for screening, and 3 times for a time trial).
At information day questions are answered, and log books are handed out.
Participants fill out these log books during their normal training program and
during the adapted training program.
At screening day, a VO2max test is performed and one shorter test time trial is
performed, this serves as a familiarization with the bike ergometer and to
establish inclusion criteria.
Time trials are performed before and after the 4 week training period and after
a recovery period. Before the time trial, a POMS questionnaire is filled out
and after the time trial a Borg scale is showed to ask for severity of the test.
Risks and discomfort are small. Athletes are used to perform maximal exercise,
which makes the VO2max test and time trials an additional average intensive
training workout. The adapted training period consists of a higher training
volume and intensity then athletes* average training program, this probably
leads to fatigue and temporary underperformance. But with sufficient recovery
afterwards, this should not cause long-lasting problems.
Because there is a risk (though very small) of overtraining, athletes will be
monitored. After every week of training, athletes will be phoned and a few
points will be checked: morning heart rate, (quality of) sleep, accomplishment
of the training protocol, and POMS questionnaire. If these data suggest that
the athlete is at risk for overtraining, he or she will be withdrawn from the
study.
We will use the following criteria: increase in morning heart rate (>20%),
worse POMS score (at least 2 points decrease in the mood state "Strength" and
at least 2 point increased score in mood state "depression","anger","fatigue",
ánd "tension"), decrease in sleep quality (>25% decrease on scale 1-10) ánd
unable to fulfil 80% of the training program. When an athlete meets all four
criteria, he/she will be withdrawn from the study for protection.
When an athlete completes the study or will be withdrawn, he/she will perform 2
weeks of recovery training (50% volume). After this recovery, he/she will
perform a final time trial. If the performance of this third time trial is
worse than the first time trial (>2% increase in time), we will advise the
athlete to take one additional recovery week at 50% volume. We will phone the
athlete after this period to check whether he/she is recovered (normal heart
rate, normal quality of sleep, normal POMS)
In short: the risks are rather small, but the advantage of this study, is that
it could lead to a training protocol which induces underperformance in a safe
and controlled manner, which, in future, could lead to the discovery of markers
to diagnose overtraining in an early stage.