Swimrun differ from most aquatic oriented multi-stage sports in that you actually run on land in a wetsuit, in-between the many swim stages and most of the time with your wetsuit fully on.
But how does wearing and running in a tight and mostly black neoprene wetsuit affect your body?
We have previously discussed the science around doing exercise in a wetsuit where studies have found that it will protect you from hypothermia, but might cause overheating. And finding that perfect balance can actually make you go longer and harder than you normally do. But doing exercise in a wetsuit this is not without risk. A recent study by Prado et al. (2017, below) has investigated this phenomenon in triathlon, a multi-sport that puts pressure on one’s overall physical capacity. As it turns out there have been 43 event-related deaths from 2003-2011 and the majority occurred during the swim stage. To date there is no clear explanation for the deaths but autopsies report evidence of cardiac abnormalities, hypothesising that immersion pulmonary oedema (IPO, a.k.a swimming induced pulmonary edema, SIPE), can be a potential cause of death. In comparison, the risk of death during a triathlon has been reported to be 1.5 per 100,000 participants compared to only half the risk during a marathon, at 0.8 for every 100,000 participants.
There are several risk factors to IPO of which one is hypertension (high blood pressure).
Prado et al set out to investigate this but also a previously unstudied factor namely heart rate variability (HRV). The aim was to determine if wearing a triathlon wetsuit properly or improperly fit, influenced resting blood pressure and HRV. It turns out that wearing a wetsuit that is too tight can negatively influence physiological parameters like blood pressure, but it’s not a stand-alone risk factor for a possible cardiac event. It should rather be seen as a strong contributing factor combined with other possible environmental factors such as race anxiety, or stress including swimming with large number of athletes simultaneously, cold and choppy water and a history of being sick.
When buying a wetsuit it’s therefore important to look beyond recommendations that a wetsuit should have a tight fit, or the general manufacturer criteria usually displayed in a height vs. weigh chart.
That’s not enough. Finding that proper wetsuit is all about the individual fit. Hence body type and composition also needs to be considered, e.g., mesomorphic, endomorphic, ectomorphic. Most people buy their wetsuit online or try it in the store. A wetsuit in the dry does not provoke the same sensations and fit compared to being used in the water. It’s a completely different feeling and this is why we recommend you to try it out first before buying it.
And remember, when you ended your last season you (hopefully) did it while peaking, i.e. being in your best shape and at your slimmest. That wetsuit might not fit you the coming season, why itâ€™s best to have 2 wetsuits, if your budget allows for it.Stay safe out there and take care of each other.
/The WoS Team
Prado A, Dufek J, Navalta J, Lough N, Mercer J
The purpose of this study was to investigate the effects of wearing a wetsuit on resting cardiovascular measures (blood pressure (BP), heart rate variability (HRV)). The influence of position (upright, prone) and wetsuit size were also explored. Participants (n=12 males, 33.3Â±12.1 years) had BP and HRV measured during six resting conditions: standing or prone while not wearing a wetsuit (NWS), wearing the smallest (SWS), or largest (LWS) wetsuit (based upon manufacturer guidelines). Heart rate was recorded continuously over 5-mins; BP was measured three times per condition. HRV was represented by the ratio of low (LF) and high (HF) frequency (LF/HF ratio); mean arterial pressure (MAP) was calculated. Each dependent variable was analyzed using a 2 (position) x 3 (wetsuit) repeated measures ANOVA (Î±=0.05). Neither HRV parameter was influenced by position x wetsuit condition interaction (p>0.05) and MAP was not influenced by position (p=0.717). MAP and LF/HF ratio were both influenced by wetsuit condition (p<0.05) with higher during SWS than NWS (p=0.026) while LF/HF ratio was lower during SWS compared to NWS (p=0.032). LF/HF ratio was influenced by position being greater during standing vs. prone (p=0.001). It was concluded that during resting while on land (i.e., not submerged in water), wearing a small, tight-fitting wetsuit subtlety altered cardiovascular parameters for healthy, normotensive subjects.