Hydration, heat and performance: how the summer affects your training and recovery
1 August 2025When the sun finally comes out, most of us leap at the chance to be more active — more walks, more outdoor workouts, more running, more ‘life’. And while being active in the summer is great for both physical and mental health, there’s one often-overlooked factor that plays a huge role in how you perform, how you recover, and how resilient your body is to injury – heat.
At the Hub, we see the impact of warmer weather on performance and recovery every single year. And it’s more subtle, and more important, than many people realise. If you’re finding yourself more tired than usual, picking up niggles, or wondering why your sessions feel so much harder, it could be your body’s way of telling you it’s under more strain than you think.
Your body works harder in the heat than you think
When you exercise in warmer conditions, your body must manage two big jobs at the same time:
- Regulate your internal temperature
- Replace fluids and electrolytes lost through sweat
That might sound simple enough, but this dual demand means your system is under more stress than usual, and it doesn’t take much to start feeling it.
Here’s what you might notice:
- Everything feels more difficult, even at your usual pace
- Your heart rate runs higher than normal
- Your muscles fatigue or cramp more quickly
- You tire faster and recover slower
- You feel heavy or sluggish, even the next day
This added stress on the body doesn’t just affect elite athletes, it affects everyone. From dog walkers and runners to people getting back into fitness. What often gets missed is how easily that heat stress builds up across a few sessions if recovery isn’t prioritised. Sound familiar? It’s often not just “a bad session” — it’s dehydration and heat stress taking their toll.
How dehydration affects your muscles
Muscles are around 75% water. When you’re not well hydrated, the water inside your muscle cells reduces, literally shrinking the cell volume. This makes muscles less efficient at contracting, which means movement feels harder and slower.
Dehydration also interferes with:
- Oxygen and nutrient delivery to your muscles
- Waste product removal post-exercise (like lactic acid)
- The electrolyte balance that helps your nerves and muscles fire properly
As a result, you’re more likely to experience:
- Muscle cramps or spasms
- Soreness that hangs around longer
- Joint stiffness and overall fatigue
- Slower or incomplete recovery
It’s not uncommon for us to see patients who feel ‘tight’ or ‘stuck’ after sessions, who actually just need a hydration review. A tired, under-fuelled muscle simply won’t perform or repair in the same way. Bottom line? If you’re not staying on top of hydration, especially in summer, you will feel it, in your sessions, your recovery, and your injury risk.
Recovery is slower in the heat
It’s not just the session itself that feels harder. Your recovery also takes a hit. In warmer temperatures, your sleep can be affected, which means your body has less opportunity to repair and replenish.
Heat, dehydration and disrupted sleep (hello, hot nights) all interfere with the body’s ability to repair itself post-exercise. You may notice:
- Heavy legs that don’t bounce back
- Delayed onset of muscle soreness (DOMS) that peaks later and lasts longer
- Energy dips that linger for days
If you’ve ever trained hard in summer and felt like you needed twice the recovery, you’re not imagining it. It’s your body doing its best to cope with a larger overall stress load — and hydration is one of the easiest ways to reduce that load.
Five ways to train smarter in summer
1. Drink before you’re thirsty
Thirst is a late sign of dehydration. Try this:
- Drink 500ml water 1–2 hours before training
- Sip 150–250ml every 20 minutes during exercise
- Replace what’s lost afterwards, especially if your clothes are soaked or you feel noticeably tired
2. Don’t skip electrolytes
Sweat isn’t just water – it contains sodium, potassium and other electrolytes. If you’re sweating heavily or training longer than 60 minutes, consider drinks that contain added electrolytes to support muscle function and reduce the risk of cramping.
3. Train at cooler times of day
Avoid peak heat times if possible (in the UK, typically between 1-4pm). Morning or evening sessions allow for better performance and recovery.
4. Adjust the intensity
It’s okay to scale your effort in warmer conditions. Training smart means adapting to what your body needs, especially if you’re noticing extra fatigue or soreness.
5. Prioritise cooling down
After training, help your body cool gradually. Sit in the shade, sip something cold, or try a cool towel. This supports faster recovery and helps bring your nervous system back to baseline.
One more thing: footwear matters too
Summer often means lighter footwear – sandals, sliders or minimalist trainers. While they’re great for airflow and comfort, they often lack the support your feet need, especially if your muscles are already fatigued from the heat.
Increased walking, harder surfaces, and reduced cushioning can overload your feet, particularly your plantar fascia, toes and ankles. If you start to notice foot, knee or hip pain, your footwear could be contributing – particularly in combination with heat and fatigue. We talked about this in our July blog and on our social media last month, so be sure to check this out if you are struggling.
Why this matters for injury prevention
Heat affects how your muscles function, how your tissues recover, and how likely you are to get injured. A tired, dehydrated muscle is less responsive, less resilient, and more prone to strain. We often see an uptick in overuse injuries, cramping, and movement compensations during summer months – all linked to reduced recovery and heat management.
Understanding the impact of environmental stressors like heat can make a huge difference to your training outcomes, and your ability to stay injury-free.
What we’re seeing at the Rehab Hub
Each summer, we help runners, gym-goers, team players and weekend warriors who are struggling with:
- More fatigue than usual
- Slower recovery between sessions
- Aches and niggles that seem to come from nowhere
Sometimes these symptoms are mistaken for overtraining or loss of fitness, when in reality they’re often the result of reduced recovery in the heat. Hydration, recovery strategies and thoughtful load management can make all the difference — and that’s where our team can help.
Final thoughts from the Rehab Hub team
We love seeing you stay active in the summer. Getting outdoors, moving more, and feeling stronger is what it’s all about. But summer training comes with its own set of challenges, and hydration and heat management are too important to ignore.
Whether you’re training for an event, trying to maintain consistency, or just want to feel better in your body, it pays to understand how heat affects performance. And more importantly, what you can do about it.
Need support with summer training or recovery?
If you’re feeling flat in your sessions, struggling to recover, or picking up more niggles than usual, book in with one of our team. We’ll assess what’s going on, tailor a plan to your needs, and help you stay on track with practical advice on hydration, recovery and load management.
Book online or give us a call — we’d love to support you!
