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This is a special one all about Heart Rate Variability
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What is heart rate
variability?
The
heart is a specialised pump that functions by regular and continuous contractions
for delivery of oxygenated blood throughout the body (Boudalas et al., 2014).
Heart rate (HR) is the number of heart beats per minute (BPM). Heart rate
variability (HRV) is the fluctuation in the time intervals between these
heartbeats (Shaffer and Ginsberg, 2017). These changes in time intervals are
dependent on the environment and the physiological state one’s body may be in
(MCcraty and Shaffer, 2015). At rest it is a favourable to have a high HRV,
whereas when exercising it may be favourable to have a low HRV. A high HRV
means the variability between adjacent heartbeats is high (spread out across a
long variability of time). A low HRV means heartbeats are rather constant. Low
HRV at rest has been shown to be a predictor of coronary heart disease (CHD)
and mortality (Dekker et al. 2000).
Fig 1. The science and application of heart rate
variability (https://hrvcourse.com/heart-rate-variability-vs-heart-rate/)
The autonomic
nervous system - what role does it play?
HRV
has proved to be a simple, useful and non-invasive method for analysing the
autonomic mechanisms through the measurement of continuous beat-to-beat
variations (Amano et al., 2001). The understanding of the significance of HRV
is still ongoing. However, it has been suggested that HRV is an important
method for assessing cardiovascular autonomic parameters that are partially
under the regulatory control of the sympathetic (fight or flight) and
parasympathetic (rest) systems (Hemingway et al., 2015).
Fig 2. Hearthmath (https://www.heartmath.org/articles-of-the-heart/the-math-of-heartmath/heart-rate-variability/)
Reliability
and Validity
Heart
rate variability has been found to be a valuable measure in a variety of sports
settings with the measurement of many factors including overtraining, recovery,
endurance training, and exercise (Makivić, Djordjevic and Willis, 2013). HRV has been shown to decrease with age due to a decrease in
vagal tone, produced by the vagus nerve (Ogliari et al., 2015). The vagus nerve
regulates many bodily functions at rest under sub-conscious control (Heart
rate, vasodilation, vasoconstriction, breathing etc…). However, exercise has
been shown to reverse this and increase HRV (An increase in HRV means our
bodies are responding well to the accumulated stimulus placed upon it). HRV
is a potentially powerful method as a basic scientific tool for better
understanding the regulation and control of the cardiovascular system. From a
practical point of view 10-15 years ago it remained to be determined if it can
also be used as a predictor of athletic condition (Aubert, Seps and Becker, 2003).
However, new research has found that HRV guided training could be a good method
to use to increase peak power in well-trained cyclists (Javaloyes et al. 2019).
What
does the new research say?
New
research conducted by Javaloyes et al. (2019) was conducted in the Sport Research Centre of Miguel Hernandez
University in Alicante, Spain and the University of Stellenbosch in South
Africa.
Seventeen
well-trained cyclists were recruited for this study and the point of the study
was to determine whether HRV could enhance the prescription of training load vs
a traditional periodisation group.
Layout of the study
- Evaluation week
- 4 Baseline weeks (common)
- Evaluation week
- 8 Training weeks (HRV
guided/Traditional)
- Evaluation week
HRV
was measured by the cyclists at home every morning with a Polar H7 chest strap,
and the heartbeat data was analysed by the researchers using lab software. From
this, a 7-day moving average of HRV was calculated. During the four baseline weeks,
participants performed about eight hours of training per week, during which the
mean and standard deviation of the HRV measurements were calculated for each
cyclist. This produced thresholds for the HRV-guided training weeks that
followed.
HRV
Group
During
the 8-week training phase an algorithm used in a previous study conducted by
Kiviniemi et al. (2007) on endurance runners was used. The
daily guide was slightly altered to allow for splits between low intensity,
threshold and HIIT days. The
overall outcome of days ended up being in the split of 66/24/10 in the low,
moderate and high intensity zones. A
big difference between this and previous research was the fact that the HRV
group were prescribed training based on a 7 day moving average
Periodisation
Group
The
group that performed the standard planned periodisation training schedule ended
up training in a similar split (64/27/9). However, the plan was a fixed
rotation and did not change according to HRV on given days. The
average training time per week for each groups was 9 hours per day.
Major
Findings
The
HRV group increased their peak power, VT2 power and power over 40 mins by 5%,
14% and 7% whereas the periodisation group hardly increased their peak power
and power over 40 mins by anything at all. These
new findings could be exciting for potential practical implications for the
future of athlete monitoring.
Practical
implications and tips for coaches wanting to use this method
1.
7 day moving
average – Watch out for changes in the 7 day moving average of HRV. If it
decreases then lowering the intensity of training could be a good idea.
2.
Daily readings –
Use daily readings to ensure consistency in the results and to see the changes
in HRV frequently
3.
Morning readings –
Ensure readings are taken in the morning before the athlete (or yourself) has
consumed food or caffeine as these can stimulate the ANS to trigger misguided
results
4.
Avoid keeping
training the same all the time – Do not just stick to the same training because
the 7-day moving average of HRV stays high. Introduce variation to avoid
monotony of the athlete.
Fig 3. https://www.pinterest.co.uk/pin/320600067202573820/
How do I calculate my heart rate variability?
1.
Buy
a heart rate monitor There are a few
chest straps (e.g. Polar and
Wahoo) and finger pulse sensors (e.g. Ithlete) that have been shown to be sufficiently accurate.
2.
There are many
apps on smartphones that can be utilised to measure HRV (Apple health, OURA,
HRV4Train, Elite HRV, Ithlete). However, not all have been validated in peer
reviewed studies therefore I would recommend using ithlete.
3.
Run an evaluation
week on what you want to improve on
4.
A baseline average
should be recorded initially over the course of 4-6 weeks, once you have a
baseline with your normal training stimulus you can adjust your training accordingly
to results
5. Devise an 8-10 week training schedule
and adjust weeks accordingly to HRV
6. Run another evaluation week to see if
improvements have been made
Is
measuring HRV expensive?
An
average polar HR monitor costs on average £80-100 depending on the model and
size of which one you purchase. Ithlete
HRV app costs £7.99 and another well renowned app called elite HRV costs £4.99
to purchase for full use to them. For
daily measurements of HRV you are looking at around £85-£110 of initial payment
which in my opinion is not too expensive for an investment into your holistic
health and performance.
Alternatives
to HRV
Subjective
athlete readiness scores
Subjective
athlete readiness scores have been shown to be a valid measurement of acute and
chronic fatigue in a recent systematic review conducted by Saw, Main and Gastin
(2016). Wellness questionnaire are simply a questionnaire given to the athlete
for them to rate how they feel. This will often cover a range of topics such as
how they slept the previous night, their current stress-level, body soreness,
and how tired they feel (Rushall, 1990). The
list of questions, and the structure of the questionnaire, is commonly designed
by the coach based on what they feel is most important factors in their athletes life. For example, a coach
working with athletes that are in
education may choose to include questions regarding educational workload, as
this is known to impose a certain degree of stress and limit physical
adaptations (Bartholomew et al. 2008). However, if you are a coach working with
elite, older athletes the need for a question like this is not necessary
allowing it to be withdrawn from the questionnaire.
Rating
of fatigue scale
The
rating of fatigue scale (ROF) has recently been showing to be a good measure of
fatigue and has good convergent validity (Micklewright et al. 2017). This
study was performed using cycling exhaustion and compared ROF against
physiological measures (subjective) and an objective measure of fatigue, rating
of perceived exertion (RPE). High convergence was found between ROF and several
physiological measures of fatigue (HR, Blood lactate concentration, oxygen
uptake, carbon
dioxide production, respiratory exchange ratio and ventilation rate). ROF and RPE correlated in the exhaustion trial
but not in the recovery stage, This demonstrated discriminant validity. ROF
is done through an 11-point Likert scale with diagrammatic selections. This two-part
system seems to make the rating easier for participants and, therefore,
provides a more accurate way of determining perceived fatigue levels. ROF
appears to have high levels of both convergent and discriminant validity making
it a useful tool in monitoring an athletes fatigue levels during a training
session and allowing for programs to be altered accordingly.
Conclusion
To
conclude, the new findings on HRV are very interesting and open up a big window
for further research into this growing area. Further research should look at
whether or not HRV is a valid measure on elite and recreational athletes as the
recent research only indicates that it can improve power in well-trained
athletes. No
recent studies to current knowledge have looked at whether or not HRV can be
used to determine the response to resistance training in elite or recreational
athletes, therefore this needs to be validified before recommendations can be
created. I
believe that if you are looking to improve performance and want a subjective
measure to do so, HRV could be a very useful tool for you to use. It can be an
indicator to you for holistic health and could allow you to subjectively choose
which days can be of higher intensities in your training schedule, and which
days you need to back off slightly to ensure we do not over train.
Authors Details
Alec
Ward
Contact
Number - 07453278459
References
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I have a BSc (Hons) in Applied Sport Science and a Merit in my MSc in Sport and Exercise Science and I passed my PGCE at Teesside University.
Now I will be commencing my PhD into "Investigating Sedentary Lifestyles of the Tees Valley" this October 2019.
I am employed by Teesside University Sport and WellBeing Department as a PT/Fitness Instructor.
My long term goal is to become a Sport Science and/or Sport and Exercise Lecturer. I am also keen to contribute to academia via continued research in a quest for new knowledge.
My most recent publications:
My passion is for Sport Science which has led to additional interests incorporating Sports Psychology, Body Dysmorphia, AAS, Doping and Strength and Conditioning.
Within these respective fields, I have a passion for Strength Training, Fitness Testing, Periodisation and Tapering.
I write for numerous websites across the UK and Ireland including my own blog Strength is Never a Weakness.
I had my own business for providing training plans for teams and athletes.
I was one of the Irish National Coaches for Powerlifting, and have attained two 3rd places at the first World University Championships,
in Belarus in July 2016.Feel free to email me or call me as I am always looking for the next challenge.
Contact details below;
Facebook: Andrew Richardson (search for)
Facebook Page: @StrengthisNeveraWeakness
Twitter: @arichie17
Instagram: @arichiepowerlifting
Snapchat: @andypowerlifter
Email: a.s.richardson@tees.ac.uk
Linkedin: https://www.linkedin.com/in/andrew-richardson-b0039278
Research Gate: https://www.researchgate.net/profile/Andrew_Richardson7
