7-Day Caffeine and Upper-Body Power in Active Women

NCT07771556 | Completed

• 1 other identifier: IR.BIRJAND.REC.1401.013
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

This study investigated the effects of a 7-day caffeine supplementation on heart rate variability, cognitive performance, and upper-body anaerobic power in active women. Thirty healthy active women aged 25-30 years participated in this double-blind, placebo-controlled trial. Participants were randomly assigned to receive either 5 mg/kg of caffeine or a placebo daily for 7 days. Heart rate variability, cognitive function (measured by the Stroop test), and upper-body anaerobic power (measured by a 20-second Wingate test) were assessed at baseline, 90 minutes after supplementation, and 30 minutes after exercise. The primary outcome was peak anaerobic power. The study aimed to determine whether short-term caffeine habituation enhances exercise performance without altering cardiac autonomic function or cognitive performance.

Conditions

Caffeine; Exercise; Physical Fitness

Keywords

Anaerobic Performance; Upper Body; Heart Rate; Dietary Supplements

Outcome Measures

Primary Outcomes (1)

• Change in Upper-Body Peak Anaerobic Power

  Peak power output (W·kg-¹) measured during a 20-second upper-body Wingate test on a cycle ergometer (Monark 891 E).

  Measured 90 minutes post-ingestion on Day 1 and Day 7.

Secondary Outcomes (7)

• Change in Cognitive Performance

  Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.

• Change in RMSSD

  Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.

• Change in SDNN

  Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.

• Change in LF Power

  Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.

• Change in HF Power

  Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.

Study Arms (2)

Caffeine Supplementation

EXPERIMENTAL

5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days.

Dietary Supplement: Caffeine

Placebo Supplementation

PLACEBO COMPARATOR

Participants received a matching placebo capsule containing flour, ingested daily for 7 days.

Dietary Supplement: Placebo

Interventions

Caffeine DIETARY_SUPPLEMENT

5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days.

Caffeine Supplementation

Placebo DIETARY_SUPPLEMENT

Matching placebo capsule containing flour, ingested daily for 7 days.

Placebo Supplementation

Eligibility Criteria

• Age: 18 Years - 30 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Active women aged 25 to 30 years
• Body mass index (BMI) between 18 and 25 kg/m²
• Physical activity readiness (based on the PAR-Q questionnaire)
• No injuries within the last month
• Non-smoking
• No cold or COVID-19 infection in the past four weeks
• No cardiovascular, metabolic, or respiratory infections in the last three months
• Normal blood pressure
• No use of anabolic steroids, central nervous system stimulants, or other sports supplements in the past six months

You may not qualify if:

• Inability to follow the protocol
• Daily caffeine intake exceeding 300 mg (assessed using an adapted FFQ)
• Consumption of alcohol or intense aerobic activity within 48 hours prior to testing
• Resistance training with weights within 72 hours prior to testing
• Caffeine consumption within 24 hours prior to testing

Sponsors & Collaborators

• Birjand University of Medical Sciences: lead

Study Sites (1)

Faculty of Sport Sciences, University of Birjand

Birjand, South Khorasan Province, 9717434765, Iran

Location

MeSH Terms

Conditions

Motor Activity

Interventions

Caffeine

Condition Hierarchy (Ancestors)

Behavior

Intervention Hierarchy (Ancestors)

Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring

Study Officials

• Mohsen Ahmadi Mohammadnia, PhD

  university of birjand

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: August 10, 2026
• First Posted: August 18, 2026
• Study Start: January 1, 2020
• Primary Completion: July 1, 2020
• Study Completion: September 1, 2020
• Last Updated: August 18, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

IR (1)