By Randall Cooper, Sports & Exercise Physiotherapist
Caffeine is one of the most researched supplements in sport - and most people are already using it every day. Coffee, tea, energy drinks, pre-workouts… but how many actually understand how it affects strength, endurance, or recovery?
In Episode 6 of Exercise Matters, Mick Hughes leads the discussion on how caffeine impacts physical performance. We break down the research, cut through the hype, and explain what actually works.
🎧 Listen to the full episode here
What Does Caffeine Do?
Caffeine blocks adenosine receptors in your brain, making you feel more alert. It also stimulates the release of adrenaline, improves diaphragm function, and - when dosed properly, improves performance.
But there’s a sweet spot, and more isn’t always better.
Endurance: Strong Evidence
Caffeine improves endurance performance. Studies show:
- +17% time to exhaustion on average
- ~1% improvement in time trials
Most effective dose: 3–6 mg/kg of body weight, taken ~60 minutes before training or racing.
It works for both trained and recreational runners, but more data is needed in female athletes.
Anaerobic & Team Sports: Yes, It Helps
For team sports (football, basketball, combat, racquet), caffeine improves:
- Number of sprints
- Acceleration/deceleration
- Offensive actions (e.g. shots, tackles)
- Success rate of skill-based tasks
It also improves jumping performance in female athletes, though not necessarily max strength.
Strength & Resistance Training: Mixed but Positive
Caffeine improves:
- 1RM strength (~4–7% in lower body)
- Muscular endurance (+6–7%)
- Repetition speed and power, depending on the dose and load
But results vary. High doses (9 mg/kg) don’t deliver more results - just more side effects.
Caffeine and DOMS: Can It Help?
Some evidence suggests caffeine reduces perceived soreness (DOMS) by 4–26% post-exercise. It doesn’t reduce actual muscle damage but can make you feel better between sessions. For athletes training multiple times a day, this can help.
How Much Should You Take?
- 3–6 mg/kg bodyweight is the sweet spot
- Start low if you’re new to caffeine use
- Avoid taking it too close to bedtime, half-life is ~5 hours
Common sources and caffeine content:
- Espresso (single): 100 mg
- Brewed coffee (250 mL): 80–150 mg
- Pre-workouts: 200–400 mg per serve
- Gels/gums: 40–100 mg
Is It Safe?
Yes, for most people, within limits:
- ≤400 mg/day for adults is considered safe
- Avoid if you have high blood pressure or poor sleep
- Not recommended in high doses for kids or adolescents
Should You Use It?
Caffeine is effective across endurance, strength, and intermittent sport. It’s legal, relatively cheap, and works fast. But it’s not magic - and it’s not for everyone. Some people don’t tolerate it well, and sleep disruption is real.
If you use it:
- Test it in training before race day
- Find your individual dose and timing
- Don’t use it every session—it’s a tool, not a crutch
