• Heart rate measurements were taken for 167 people on 86 scaffolds. • Heart rate increased with distance and vertical movement of the worker on scaffold. • Heart rate increased with weight and decreased with age of worker. • No relationship between geometric characteristics of scaffolds and heart rate was identified. • Workers aged 50+ showed increased working time with heart rate approaching maximum heart rate. This paper evaluates strain of worker’s organism when working on scaffolds. Heart rate (HR) was measured for 167 people working on 86 scaffolds. The relationships between HR and scaffold characteristics, worker parameters, age, climate, and thermal indices (WBGT, UTCI, PET, and SET*) were examined. Distance covered and vertical movement on scaffolding caused HR increase. Higher worker weight and age led to HR increase and decrease, respectively. Scaffolding dimensions did not influence HR. Workers aged 50+ worked longer at HR approaching HR max . HR trends depended on the type and value of thermal index. At cool thermal sensations (UTCI, SET*), HR slightly increased with indices values, and the highest ratio of time with high HR (80–100 % HR max ) appeared. At extreme hot (WBGT) and very hot (UTCI, PET) thermal sensations, HR increased with indices values, while there was a lower ratio of time with high HR. The lowest HR occurred in around-comfort conditions.

• Helicopter crews solved rescue missions with rope and hoist, in randomized sequence. • NASA Task Load Index workload, heart rate, and heart rate variability were analyzed. • Workload was lower in hoist operations for all crewmembers, most markedly for pilots. • Findings were consistent across mission terrain types and operational flight phases. • Physiological measures aligned with workload among pilots and rescuers, but not among physicians. High workloads can deplete cognitive capacity, impairing individuals’ ability to meet task demands and increasing the likelihood of human error. Helicopter rescue operations are inherently complex and require effective multitasking by all crewmembers. This study aimed to quantify subjective workload and physiological activation associated with two different rescue methods, hoist operations and rope operations, in a three-crew Helicopter Emergency Medical Service. The National Aeronautics and Space Administration (NASA) Task Load Index was used to assess workload. Heart rate and heart rate variability were used as markers for physiological activation. Crews performed fifty-five standardized rescue missions covering four distinct terrain categories: alpine, gorge, forest, and vertical environments. Each mission was solved with both rope and hoist rescue methods, in randomized sequence. Linear mixed-model regression analyses were used to account for repeated measures within individuals. Across all mission phases, pilots (n = 4), physicians (n = 3), and rescuers (n = 4) reported lower workloads during hoist operations than during rope operations. For pilots and rescuers, hoist operations were also associated with lower physiological activation. The opposite was found in physicians, who acted as hoist operators. Rescue method affected pilots most markedly, their mean workload scores during active mission being 35 [19,52] for hoisting versus 53 [37,70] for rope operations (R 2 = 0.76, p <0.0001). Analogously, pilot mean heart rate was 80 [57,103] during hoisting compared to 88 [65,111] during rope operations (R 2 = 0.91, p <0.0001). A reduction in workload could contribute to improved flight safety, favouring hoist as rescue method.