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Heat stress and workload associated with sugarcane cutting - an excessively strenuous occupation!


Chronic kidney disease not associated with traditional risk factors (sometimes called Mesoamerican nephropathy) is prevalent in male agricultural labourers, particularly sugarcane cutters, in Central America and Mexico regions [1]. Strenuous work in a hot environment with dehydration is believed to be a key causal factor [1]. The aim of this study was to assess the level of heat stress and workload in sugarcane cutters.


45 sugarcane cutters (34(12) y; range 18 - 57 y) from El Salvador were studied during the 2015 harvest (Feb-April). Heart rate (HR, Polar) was recorded in 10-11 workers per day, during 7 workdays. Weather data was collected using two weather stations (Weatherhawk, QuesTemp °34). Outdoor Wet Bulb Globe Temperatures (WBGT) was calculated (WBGT (outdoor) = 0.7WB + 0.2G + 0.1DB) via the QuesTemp °34. HR data were expressed a percentage of maximal HR (%HRmax). A regression equation was used to predict HRmax (208 - 0.7 × age) [2].


Sugarcane cutters worked on average for 7:30 hours (range 3:20 - 9:36 hours). In the field, WBGT reached 32.1°C (95% confidence interval [CI]: 33.0°C to 31.1°C), with 79 % (95% CI: 87 to 71%) of the day spent working at a WBGT above 26°C (threshold limit for continuous harvesting at 100 % [3]). Heart rates averaged 54 %HRmax (95% CI: 57 to 52 %HRmax) across all workdays. Workers spent 4:44 hours (95% CI: 5:19 to 4:09 hours) working at ≥50%HRmax and 2:48 hours (95% CI: 3:21 to 2:15 hours) working <50%HRmax.


Sugarcane cutting is repetitive high-intensity work carried out in high heat stress conditions. Workers spent over half the workday (including rest breaks) working at and above 50% of their HRmax. This HR intensity is similar to that exhibited in the first 12 hours of adventure racing (64%HRmax [4]) and higher than that maintained by soldiers during multi-day operations (30 - 40% of aerobic power [5]).


The cardiac strain of sugarcane cutting is similar to that associated with very prolonged, competitive exercise and higher than that typically associated with self-paced hard work. Yet, sugarcane cutters maintain this work intensity daily throughout the harvest (~6 months).

Figure 1

Heart rate (1 min intervals) during one workday for two sugarcane workers.


  1. 1.

    Wesseling C, Crowe J, Hogstedt C, Jakobsson K, Lucas R, Wegman DH: Resolving the enigma of the mesoamerican nephropathy: a research workshop summary. American Journal of Kidney Diseases. 2014, 63 (3): 396-404. 10.1053/j.ajkd.2013.08.014.

  2. 2.

    Tanaka , Hirofumi , Monahan , Kevin D, Seals , Douglas R: Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology. 2001, 37 (1): 153-156. 10.1016/S0735-1097(00)01054-8.

  3. 3.

    Crowe , Jennifer , Wesseling , Catharina , Solano , Bryan Román , Umaña , Pinto Manfred, Ramírez , Robles Andrés, Kjellstrom , Tord , Nilsson , Maria : Heat exposure in sugarcane harvesters in Costa Rica. American Journal of Industrial Medicine. 2013, 56 (10): 1157-1164. 10.1002/ajim.22204.

  4. 4.

    Lucas SJ, Anglem N, Roberts WS, Anson JG, Palmer CD, Walker RJ, Cotter JD: Intensity and physiological strain of competitive ultra-endurance exercise in humans. Journal of sports sciences. 2008, 26 (5): 477-489. 10.1080/02640410701552872.

  5. 5.

    Myles WS, Eclache J, Beaury J: Self-pacing during sustained, repetitive exercise. Aviation, space, and environmental medicine. 1979, 50 (9): 921-924.

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Correspondence to Rebekah AI Lucas.

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  • Chronic Kidney Disease
  • Heat Stress
  • Aerobic Power
  • Heat Stress Condition
  • Strenuous Work