Research ArticlePHYSIOLOGY

Extreme events reveal an alimentary limit on sustained maximal human energy expenditure

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Science Advances  05 Jun 2019:
Vol. 5, no. 6, eaaw0341
DOI: 10.1126/sciadv.aaw0341
  • Fig. 1 Metabolic scope and duration.

    (A) Blue circles and trend line: Short events (<0.1 days; 800 m to marathon). Red circles: Events 0.5 to 95 days. Gray open circles: Estimates for ultramarathon world records and other well-documented endurance events. Purple cross: Other high metabolic scope measurements. Red trend line with 95% confidence interval (CI): SusMS versus duration limit (analysis A in table S2). Data: table S1. (B) SusMS versus duration relationship [unlogged and redrawn from (A); analysis A in table S2] flattens out at ~2.5× BMR. Cumulative average metabolic scope (see Materials and Methods) is shown for elite cyclists over a touring season, arctic trekking, RAUSA runners, and pregnancy and lactation. (C) Habitual metabolic scope (“physical activity level”) for n = 130 cohorts from a diverse global sample (29) cluster below 2.5× BMR (red line).

  • Fig. 2 Observed and predicted energy expenditures for RAUSA athletes.

    (A) Observed versus predicted TEE and its components. TEF, thermal effect of food; RUN, running expenditure. Observed columns depict means (±SD) for all subjects. (B) Differences from predicted TEE for subjects at Week 1 and the final week (see Materials and Methods and Eqs. 4 and 5).

  • Fig. 3 Maximal energy intake.

    (A) Estimated energy intake, calculated from metabolic scope and weight change, is consistent across overfeeding (red inverted triangles), endurance (blue triangles), and pregnancy (green inverted triangle) studies and is unrelated to event duration (P = 0.51, r2 = 0.01, least squares regression; dashed line). (B) Weight change (in kg/day) versus metabolic scope (×BMR) for endurance (red squares), pregnancy (green square), and overfeeding (blue squares) studies (table S1). Reduced major axis regression (red line) and 95% CIs (gray lines) are indicated.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/6/eaaw0341/DC1

    Fig. S1. TEE and FFM.

    Fig. S2. Cumulative average SusMS of RAUSA runners reconstructed for the duration of the event.

    Fig. S3. Estimated energy intake at varying equivalencies of weight loss per BMR.

    Fig. S4. Isotope enrichments for a representative subject, RS2.

    Table S1. Metabolic Scope, duration, and weight loss.

    Table S2. Linear regressions for SusMS versus log10 duration.

    Table S3. Pre-Race (Pre-), Week 1 (W1), and final week (Final) measures.

    Table S4. Results of isotopic analyses.

    References (4148)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. TEE and FFM.
    • Fig. S2. Cumulative average SusMS of RAUSA runners reconstructed for the duration of the event.
    • Fig. S3. Estimated energy intake at varying equivalencies of weight loss per BMR.
    • Fig. S4. Isotope enrichments for a representative subject, RS2.
    • Table S1. Metabolic Scope, duration, and weight loss.
    • Table S2. Linear regressions for SusMS versus log10 duration.
    • Table S3. Pre-Race (Pre-), Week 1 (W1), and final week (Final) measures.
    • Table S4. Results of isotopic analyses.
    • References (4148)

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