The aim of this study is to evaluate the acute effects of beetroot juice and caffeine, consumed individually or in combination, on lower-limb strength and muscular endurance in physically active women. The main questions it aims to answer are:

• Does the co-ingestion of beetroot juice and caffeine enhance lower-limb strength and muscular endurance more than either substance alone or a placebo?
• How do the acute effects of beetroot juice interact with caffeine on physical performance?

The study was conducted using a randomized, crossover design to evaluate the following four conditions:

Beetroot juice with placebo Caffeine with placebo Beetroot juice with caffeine Placebo only

Each participant completed all conditions, with a sufficient washout period between sessions to eliminate potential carryover effects. This design allowed for a direct comparison of the acute effects of each supplementation strategy on lower-limb strength and muscular endurance.

Participant Protocol

Participants consumed their assigned supplement on a single testing day for each condition. After supplementation, they performed standardized tests to measure lower-limb strength and muscular endurance. Progress was monitored, and data from all conditions were collected to assess the acute effects of each intervention.

Inclusion Criteria:

• Minimal experience of six months of strength training
• Be familiarized with the exercise test: counter movement jump (CMJ), barbell back squats, leg press and knee extension.

Exclusion Criteria:

• Supplementation consumption
• Sports injuries