Pilates is one of the most popular forms of exercise among older adults worldwide. However, no study has measured how many calories a Pilates session burns or how hard the body works during it in people aged 60 and over. This information is important for exercise professionals who prescribe Pilates for health promotion goals such as weight management and cardiovascular fitness.

This study will measure the energy cost and metabolic intensity of two types of Pilates - mat Pilates and equipment-based Pilates - in older adults using a portable indirect calorimetry system (Cosmed K5). Results will be compared to treadmill walking at 4.8 km/h, a well-established moderate-intensity activity.

Twenty men and women aged 60 years or older with at least 6 months of continuous Pilates experience will complete three exercise sessions in a randomized order: (1) mat Pilates, (2) equipment-based Pilates, and (3) treadmill walking. Each Pilates session will consist of 9 exercises, with stretching exercises used as warm-up and cool-down and 7 strengthening exercises performed in the main portion of the session (~50 min). Oxygen consumption, energy expenditure, heart rate, and perceived exertion will be measured throughout each session.

This is a randomized crossover acute intervention trial conducted at the Human Movement Biodynamics Laboratory, Center for Health Sciences, Universidade Estadual do Norte do Paraná (UENP), Jacarezinho, Paraná, Brazil.

Twenty older adults (men and women; aged ≥ 60 years) with at least 6 months of uninterrupted Pilates practice will be recruited. Participants will complete three experimental sessions in a randomized order (randomization.com): (1) mat Pilates, (2) equipment-based Pilates, and (3) treadmill walking at 4.8 km/h. A minimum washout of 48 hours will be observed between sessions.

Before experimental sessions, participants will undergo anthropometric assessment, body composition by dual-energy X-ray absorptiometry (DXA; Lunar Prodigy Advance), and a maximal graded treadmill test (modified Balke protocol) to determine peak VO2. Familiarization sessions will be held one week prior to data collection.

Each Pilates session will include 9 exercises: 1 stretching exercise as warm-up, 7 strengthening exercises as the main portion of the session (~50 min), and 1 stretching exercise as cool-down. Strengthening exercises will be performed in 3 sets of 10 repetitions with 1-minute rest intervals. Mat Pilates will use body weight and accessories (Swiss ball, elastic bands, foam roller, magic circle). Equipment-based Pilates will use Reformer, Cadillac, Ladder Barrel and Step Chair. The treadmill walking session will consist of 50 minutes at 4.8 km/h (1% incline), preceded by a 5-minute warm-up and followed by a 5-minute cool-down (warm-up and cool-down periods excluded from analysis).

Energy cost and metabolic intensity will be measured using the Cosmed K5 portable indirect calorimetry system (breath-by-breath). Resting metabolic rate will be estimated from the final 5 minutes of a 20-minute supine rest period before each session. Metabolic intensity will be expressed in METs using the older adult reference value (1 MET₆₀ = 2.7 mL/kg/min). Rating of perceived exertion (Borg CR-10) will be assessed after each exercise set (Pilates) or every 5 minutes (walking); session RPE will be recorded 30 minutes after session completion.

All sessions will be held between 9:00-10:00 AM in a temperature-controlled room (22°C; 40-60% relative humidity). Participants will receive a standardized pre-exercise meal (28 g carbohydrate, 12 g protein, 1.2 g fat; 174 kcal) 30 minutes before each session, following an 8-hour overnight fast.

Statistical analysis: Data normality will be assessed using the Shapiro-Wilk test. Descriptive statistics will be expressed as mean ± SD. A two-way repeated-measures ANOVA (protocol × time) will be used to compare conditions across time points. Mauchly's test will assess sphericity; Greenhouse-Geisser correction will be applied if violated. Post-hoc pairwise comparisons will use Bonferroni correction. Effect sizes will be reported as partial eta-squared (η²p). Cohen's d will be calculated for pairwise comparisons. Significance level: p < 0.05. Analyses will be performed using SPSS 25.0.

Inclusion Criteria:

• Age 60 years or older;
• Body mass index (BMI) between 22 and 27 kg/m²;
• Not currently undergoing dietary treatment or program for weight gain or loss;
• No severe musculoskeletal disorders (e.g., osteoarthritis grade III or IV, moderate-to-severe pain ≥ 4 on the NRS 0-10 scale) or neurological conditions (e.g., Parkinson's disease, Alzheimer's disease, multiple sclerosis);
• Continuously practicing Pilates for at least 6 months prior to enrollment, with a minimum frequency of twice per week.

Exclusion Criteria:

• Chronic decompensated conditions that may pose health risks during exercise (e.g., uncontrolled hypertension, bronchitis, asthma);
• Any history of cardiovascular events (e.g., coronary artery disease, stroke, heart failure, arrhythmias, valvular heart disease);
• Decompensated metabolic diseases or use of medications with recognized direct impact on energy and glycemic metabolism, including antidiabetics and systemic corticosteroids;
• Positive response to any item on the Physical Activity Readiness Questionnaire (PAR-Q).

Individual participant data will not be shared. The Ethics Committee of Universidade Estadual do Norte do Paraná did not authorize the sharing of individual participant data.