This June, I was asked to write a short intro to my club's monthly newsletter and it seemed to go down quite well so I thought I'd add it to my blog (with a bit of editing to reflect the new audience).
Dear Athletes,
With
the beginning of Summer 2017 we are now officially in ‘race-season’, I'm sure many of you have raced at high-profile and grass-roots events both
abroad, and domestically already.
On
race day, we push ourselves hard, often to the limit, and it's likely that your
peak performances this year will follow a consistent block of training with an
appropriate tapering period before the main event. I thought that as we will
likely all be doing at least one race effort this year, now would be a good
time to talk about the importance of balancing recovery and training load.
To maximise the physiological
adaptations that lead to improved performance you will need to balance training
Duration, Intensity and Recovery. Recovery is arguably the most
important factor in a training programme. However, recovery does not always
involve simply not training, or putting your feet up for the afternoon. Intense
training sessions disrupt our body’s systems and processes, and the effects can
last from a few hours up to several months if the athlete has severely
over-trained. It is important that we are resting after these sessions but also
before we go into them. The concept that underlies this training principle is
the process of Sympathetic (fight or flight) Activation and Parasympathetic
(rest and digest) Withdrawal of the autonomic nervous system during
exercise. At rest, parasympathetic tone is high and regulatory body functions
such as digestion, heart rate, and skeletal muscle activation are running in
the background, unperturbed. When we exercise, the brain withdraws the output
of parasympathetic neurons and increases sympathetic outflow – this enables our
heart rate to increase to near maximum, dilatation of blood vessels,
recruitment of large numbers of muscle fibres, and redistribution of
blood to the working muscles while reducing it to lower-priority areas
(e.g. the gastric system). This process is regulated by both volitional
mechanisms e.g. pedalling harder, and feedback loops that are proliferated by
chemical signals from neurotransmitters. The thing is – when you stop
exercising, you simply stop. However, while your heart rate can go back down to
near-resting levels fairly quickly, it takes time for the other processes
described to recover and for our bodies to return to their resting set-point (homeostasis).
High levels of neural output mean that the neurons of the sympathetic nervous
system can remain excited for prolonged periods following very intense exercise.
On top of prolonged elevated
sympathetic activation there can also be a delay in parasympathetic
re-activation following exercise-stimulated withdrawal due to high levels of
circulating hormones. This double whammy is the reason your heart is still
pounding and you can’t get to sleep after a heavy track, swim or turbo session
in the evening! What is the impact of this on performance? If the sympathetic
system remains activated it will become fatigued: several studies have shown
that multiple hard-days result in diminished sympathetic neural output, causing
reductions in muscular strength, cardiac output, and motor-pattern coordination
– hence, reduced speed/increased perception of effort.
Based on what I’ve written so far it may seem like
I’ve strongly advocated against the inclusion of such strenuous training. The
point I want to get across is that you can’t go hard all the time and expect to
see consistent improvement. The practical information of this article is that
both light-intensity (<75% Max heart rate) and heavy-intensity exercise
(>85% Max HR) stimulate physiological adaptations that facilitate improved
endurance. Lower intensity exercise (LIT) does not cause the disruptions to
autonomic balance that persist after exercise, but high-intensity exercise (HIT)
does. HIT increases maximal exercise capacity while LIT increases the
capability to absorb large training volumes.
Both domains, or zones, have benefits. Yet amateur
triathletes frequently train in the middle of these zones. Training at this
intensity still yields benefits, especially if the athlete is new to the sport
as any training stimulus would produce improvement. For the more experienced
athlete who wants to maximise their training hours it is necessary to reduce
the time spent in the middle zone. This middle-intensity training (MIT) is
often performed between the lactate threshold, which is where your blood
lactate increases above resting levels, and typically occurs at >75% HRMax,
and the anaerobic threshold, which typically occurs at ~85-90% MHR, and demarks
the high-intensity domain. Mid-intensity exercise may feel like you’re working
hard but it produces greater levels of neural and muscular fatigue than LIT,
additionally it is not intense enough to elicit the adaptations seen after HIT.
Ironically, it is the time-conscious athlete who must
feel like they are maximising every minute of training, who pushes themselves
too hard on their easy days. Thus, based on what I see on Strava every day
there is very little difference between ‘race-pace’ and their ‘easy-pace’. This
delta needs to be increased to truly maximise your training sessions. As with
all things in life, it helps to follow the 80:20 rule – have 80% of your
training be at <75% of your HRMax, with at least 10 of the remaining 20%
being >85% HRmax. The result will be that you are fresher for the harder
sessions by not going into them fatigued, able to maximise your sympathetic
output during harder sessions, and gaining positive adaptations from the
lower-intensity exercise without delaying recovery.
Domain
|
HR Range
|
Effort Duration
|
Recovery
|
Adaptation
|
Low Intensity (LIT)
|
<75% Max
|
10 mins to >12 hours in some cases!
|
Usually low (<24hrs) but depends on duration
|
Increased capillaries and mitochondrial enzymes,
joint angle specific efficiency improvements related to motorneuron learning
|
Mid Intensity (MIT) (Often race-intensity for
sportive/half-ironman athletes)
|
75-85%
Max
|
10
mins to 5 hours
|
Depends
on duration but always longer and more pronounced than an equivalent time at
low intensity
|
Blend
of L and H intensity adaptations but increased blood lactate diminishes LIT
gains and reduced intensity diminishes HIT gains.
|
High Intensity (HIT)
|
>85-90% Max
|
30 seconds to 120 minutes – large range of intensity
within this zone
|
>24 hours but usually 48 hours before maximal
outputs can be reached again
|
Increased cardiac output, improved oxygen economy,
increased lactate elimination.
|
I hope this information helps everyone more
carefully plan their training and racing this year. Comment or tweet me @james_jogs to discuss!
Yours in triathlon,
James D