The Impact of Acute Exercise in the Heat on Breast Milk Production and Composition in Lactating Women

NCT07036640 | Recruiting

• 1 other identifier: IRB-FY25-26
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

This clinical trial aims to determine whether heat stress alters 24-hour breast milk production and composition following an acute bout of exercise in the heat among lactating women. The main questions are:

1. 1.To ascertain whether heat stress alters 24-hour breast milk production following acute exercise in the heat among lactating women. We hypothesize that breast milk production will decrease to a greater extent following acute exercise in the heat compared to acute exercise with no heat stress. Lactating mothers will complete an acute exercise bout at 40% of their peak oxygen consumption (VO2peak) for 60 mins in a hot (36 °C, 40% relative humidity) and thermoneutral environment (20 °C, 20% relative humidity). Participants will record their total breast milk production in a 24-hour period using an infant scale.
2. 2.to discover whether heat stress impacts the energy composition of breast milk following acute exercise in the heat among lactating women. We hypothesize that energy density will decrease to a greater extent following acute exercise in the heat compared to acute exercise with no heat stress. Participants will use a manual expression breast pump to collect 10 mL of breast milk from each breast immediately and 24 hours post-exercise. Energy density (lactose, protein, and lipid content) will be assessed via enzyme-linked immunosorbent assays.

Conditions

Lactation

Keywords

Lactation; Exercise; Heat Stress

Outcome Measures

Primary Outcomes (2)

• Breastmilk Composition

  Breastmilk lipid, protein, and lactose content

  Measured 24hr before exercise, one hour post-exercise, and 24hr post exercise for each condition

• Breastmilk Production

  Breastmilk production (lactation)

  Collected 24-hour before exercise, 1-hour post-exercise, and 24-hour post-exercise

Secondary Outcomes (3)

• Core temperature

  Collected every minute for 60 minutes during exercise

• Heart rate

  Collected every minute for 60 minutes during exercise

• Skin temperature

  Collected every minute for 60 min during exercise

Study Arms (2)

Heat exposure

EXPERIMENTAL

Heat exposure in environmental chamber during exercise (60 mins)

Other: Heat exposure

Thermoneutral Condition

NO INTERVENTION

Thermoneutral temperature (non-heat exposure condition)

Interventions

Heat exposure OTHER

Heat exposure during exercise

Heat exposure

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Currently breastfeeding or pumping expressed breastmilk for their 6-week to 24-month infants
• Aged 18-45 years old
• Delivered their infants between 37-42 weeks of gestational age

You may not qualify if:

• Obsterical complications during pregnancy
• multiple gestation
• Chronic disease (i.e., diabetes, hypertension, metabolic disease)
• Heat illnness in the last 3 month

Sponsors & Collaborators

• Providence College: lead

Study Sites (1)

Providence College

Providence, Rhode Island, 02918, United States

RECRUITING

Related Publications (4)

• Nommsen LA, Lovelady CA, Heinig MJ, Lonnerdal B, Dewey KG. Determinants of energy, protein, lipid, and lactose concentrations in human milk during the first 12 mo of lactation: the DARLING Study. Am J Clin Nutr. 1991 Feb;53(2):457-65. doi: 10.1093/ajcn/53.2.457.

  PMID: 1989413 BACKGROUND

• Woodward DR, Cumming FJ. Do ambient temperature and humidity influence the breast-milk intake of babies? J Paediatr Child Health. 1990 Dec;26(6):347-50. doi: 10.1111/j.1440-1754.1990.tb02450.x.

  PMID: 2073422 BACKGROUND

• Saint L, Smith M, Hartmann PE. The yield and nutrient content of colostrum and milk of women from giving birth to 1 month post-partum. Br J Nutr. 1984 Jul;52(1):87-95. doi: 10.1079/bjn19840074.

  PMID: 6743645 BACKGROUND

• Miller EM, Aiello MO, Fujita M, Hinde K, Milligan L, Quinn EA. Field and laboratory methods in human milk research. Am J Hum Biol. 2013 Jan-Feb;25(1):1-11. doi: 10.1002/ajhb.22334. Epub 2012 Oct 29.

  PMID: 23109280 BACKGROUND

MeSH Terms

Conditions

Breast Feeding; Motor Activity; Heat Stress Disorders

Condition Hierarchy (Ancestors)

Feeding Behavior; Behavior; Wounds and Injuries

Study Officials

• Margaret C Morrissey-Basler, PhD

  Providence College

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Margaret C Morrissey-Basler, PhD

CONTACT

4018650219; mmorri17@providence.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: June 16, 2025
• First Posted: June 25, 2025
• Study Start: July 10, 2025
• Primary Completion: May 1, 2026
• Study Completion: May 1, 2026
• Last Updated: June 25, 2025

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF
• Time Frame: Data will be shared following the completion of the study.

Locations

US (1)