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    Expert advice for working out in the heat

    on July 14, 2022



    With summer temperatures scorching to unprecedented levels, Dr Sam Shepherd (pictured below), Senior Lecturer in Sport & Exercise Nutrition at Liverpool John Moores University, provides his invaluable advice for exercising in the heat. 

    Here, as reported in the Metro newspaper, Dr Shepherd, a researcher for CurraNZ, gives his essential tips on hydration and preventing exertional heat stress. 

    1. Hydration - 'use electrolyte replacements straight away'

    Replacing water loss from sweat is essential to prevent compromised performance and capacity to exercise.

    Dr Shepherd says: “Typically, we might sweat between from 0.5-1L an hour. If you exercise in the heat, as a general rule, that could double your sweat rate to between 1-2 litres an hour.

    “To compensate, try to replace fluids in line with your sweat rate, to prevent dehydration.

    “The reality is that it’s difficult to replace that amount of fluid to keep up with a high sweat rate, so your goal is to prevent excessive body water loss. Lose 3% of your body weight during exercise and this is when you start to suffer.

    “Start using an electrolyte replacement straight away – particularly if you’re a runner or triathlete, use it throughout the training session or race.”

    Unnecessary expense isn’t required when it comes to electrolytes, either.  

    He says: “Coconut water has been marketed as a hydration alternative, because of its high potassium content. But for most people, plain simple water, or a beverage with an electrolyte effervescent tablet, is sufficient and cost effective.”  

    2. Preventing effects of heat stress

    Exercising in the heat is very stressful on the body and challenges its ability to regulate temperature. This can lead to many negative effects, such as symptoms of heat stress, increased fatigue and reduced performance.

    Dr Shepherd observes that research on CurraNZ has found several benefits when exercising in hot conditions1. The supplement promotes blood flow, whilst being an antioxidant and natural anti-inflammatory.

    He says: “We’re seeing that blackcurrant extract can have a large impact on reducing intestinal permeability and heat-induced cell damage that occurs with exertional heat stress.

    “Gastro-intestinal damage and stress is common and leads to symptoms such as dizziness, stitch, nausea and vomiting and affects up to 90% of endurance athletes.”

    The berry extract supplement is great for helping reduce fatigue during exercise, too.

    He says: “We’ve seen that blackcurrant extract substantially improves fat burning in normal and hot conditions and spares carbohydrate, which is a good thing as it leads to lower fatigue.

    “Interestingly, a study on runners in the heat showed that CurraNZ sent fat burning rates closer to those usually seen in normal conditions, with increases of 30%. We don’t know how it is doing this, but it is a good finding for anyone who is unacclimatised and training or racing in these environments.”   


    CurraNZ References 

    1. Lee et al. Anthocyanin-rich blackcurrant extract preserves gastrointestinal barrier 1 permeability and reduces enterocyte damage but has no effect on microbial translocation and inflammation after exertional heat stress, IJSNEM (in press) doi: 10.1123/ijsnem.2021-0330.
    2. Lee et al. Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat, JSMAS doi:10.1016/j.jsams.202.02.017