Caffeine capsules and gum for strength and power
What it found
In 15 strength-trained men, caffeine taken as a capsule or as chewing gum improved some measures of lower-body strength, power and jump height compared with a placebo.
Just over half the men showed improvements beyond normal day-to-day variation on key measures.
What they found
Studies in people
Knee extensor strength
Average peak torque and power at 60 degrees per second were higher after both the caffeine capsule and the gum than after placebo. The capsule group rose about 11.2% and 14.1%, the gum group about 7.3% and 11.4%.
Knee extensor isometric
Maximum isometric strength at 45 degrees was higher after the capsule than placebo, up about 10.1%. At 60 degrees it was higher after the gum than placebo, also up about 10.1%.
Knee flexor measures
Time to peak torque at 60 degrees per second was higher after the gum than placebo, up about 18.2%. Average rate of force development at 60 degrees per second was higher after both the capsule and the gum, up about 24.1% and 20.6%. Average power at 180 degrees per second was higher after the capsule, up about 18%.
Vertical jump
Vertical jump height was higher after both the capsule and the gum than after placebo, up about 5.5% and 6%.
Individual responses
Using a smallest worthwhile change threshold, more than about half the men exceeded it on key measures. The capsule had slightly higher responder rates for strength measures, while the gum did better on time-dependent measures.
Other measures
There were no differences between conditions for many other strength measures of the knee extensors and flexors.
What the authors conclude
“Caffeine supplementation in CC and CG forms significantly enhanced lower-body strength, power, and vertical jump height in strength-trained males, with over ~50% of participants exceeding the SWC thresholds across key performance metrics.”
Also in their conclusions
- They conclude that caffeine in both capsule and chewing gum forms is an effective aid for enhancing lower-body strength and power in strength-trained males.
- They say the capsule showed higher responder rates for strength parameters, while the gum provided distinct benefits in time-dependent measures.
- They advise considering individual response variability, which may be influenced by genetic factors, and support the practical use of both forms.
How it was done
The authors wanted to compare two popular ways of taking caffeine, capsules and chewing gum, and to look at how much individuals differ in their response. They note that chewing gum is absorbed faster, and that people vary in how much caffeine helps them.
Fifteen strength-trained men (average age 25, weight 75 kg, usual caffeine intake 66 mg a day) took part in a randomised, cross-over, placebo-controlled study. Each man took caffeine chewing gum, a caffeine capsule, or a starch placebo capsule on separate occasions, about 3 to 4.5 mg of caffeine per kg of body weight, with a week between sessions. They did a vertical jump test and then knee strength and power tests.
What it can’t tell you
- This was a small study in 15 strength-trained men, so the results may not apply to women, other training backgrounds, or the general population.
- The men were all low caffeine consumers, so the findings may differ for people who regularly take in more caffeine.
- The study did not measure caffeine levels in the blood, so it cannot show how absorption differences affected performance.
Who paid
- Conflicts
- No potential conflict of interest was reported by the author(s).
- Authors work at
- Shahid Beheshti University, Iran; Shiraz University, Iran; University of Chichester, UK
The paper
- Title
- Individual responses to encapsulated caffeine and caffeine chewing gum on strength and power in strength-trained males
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Teimouri-Korani H, Hemmatinafar M, Willems ME, Rezaei R, Imanian B (2025). Individual responses to encapsulated caffeine and caffeine chewing gum on strength and power in strength-trained males. Journal of the International Society of Sports Nutrition. doi:10.1080/15502783.2025.2495228Free full textPubMed 40249126DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error