Moderators of metabolic threshold adaptations: a systematic review and meta-analysis
6 affiliations
- 1Department of Exercise Physiology, Orthopedic Clinic OrthoSport Banja Luka, Banja Luka, Bosnia and Herzegovina.
- 2Faculty of Kinesiology, University of Split, Split, Croatia.
- 3High Performance Sport Centre, Croatian Olympic Committee, Zagreb, Croatia.
- 4Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, Kelowna, Canada.
- 5Faculty of Sports Ensenada, Universidad Autónoma de Baja California, Baja California, Mexico.
- 6Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Abstract
Optimal training intensity relative to individual metabolic thresholds remains ambiguous despite its fundamental importance in endurance sports. The present pre-registered systematic review and meta-analysis (PROSPERO: CRD420251020702) evaluated the relative influence of potential moderators on adaptations in the aerobic (AeT) and anaerobic (AnT) thresholds. The primary outcome variable was the magnitude of change in physiological threshold values from pre- to post-intervention, quantified through power output (W), speed (km/h), or oxygen uptake metrics (VO 2max ). Three-level meta-analytic models with cluster-robust variance estimation quantified Log Response Ratio effect sizes across 13 studies (24 intervention groups, 338 participants). Among the substantive moderators examined ( i.e. , training intensity, participant status, and intervention length), training intensity relative to the metabolic threshold showed the most consistent association with changes in threshold-related outcomes. For AeT ( k = 9), a significant effect of training intensity was observed ( p = 0.017), with supra-threshold training showing the largest improvement (+38.7%) compared with at-threshold (+14.7%) and sub-threshold (+18.4%) training. For AnT ( k = 15), a significant categorical effect of training intensity was observed ( p = 0.008), with post-hoc comparisons revealing greater adaptations for supra-threshold versus sub-threshold training ( p = 0.010), alongside a graded descriptive pattern across categories (below: +2.6%, at: ∼+7%, above: +12.2%). However, substantial heterogeneity persisted (AeT: I ² ≈ 89%; AnT: I ² ≈ 53%), likely reflecting threshold identification bias ( e.g. , lactate vs. gas analysis) and varying background training distributions. These findings identify training intensity as a primary moderator associated with threshold adaptations within the current literature, with supra-threshold metabolic range consistently outperforming at- or below-threshold prescriptions within the limited supra-threshold ranges represented in the included studies. Therefore, individualized, supra-threshold training with regular reassessment seems to be recommended to optimize individual training responses. However, substantial heterogeneity and methodological variability warrant caution, and further well-controlled studies are needed before definitive training recommendations can be made.
Related
- Serum vitamin D and fracture risk in children and adolescents: A systematic review and meta-analysis highlighting age and altitude as key moderators.
- The effect of re-warm up and its moderators on performance enhancement and rating of perceived exertion in team-sport athletes: A systematic review and three-level meta-analysis
- Dose–response relationships between temporal variables of blood flow restriction exercise and physiological adaptations: a systematic review and meta-analysis
- Shoulder Injuries and Sport-Specific Shoulder Adaptations in Judo Athletes: A Systematic Review
- Imatinib Resistance in Chronic Myeloid Leukemia Is Associated with Distinct Metabolic, Oxidative, and Autophagic Adaptations in K562-Derived Cell Sublines
BibTeX
@article{peric2026moderators,
title = {{Moderators of metabolic threshold adaptations: a systematic review and meta-analysis}},
author = {Ratko Peric and Zoran Nikolovski and Dario Vrdoljak and Antonela Karmen Ivisic and Isaac A Chavez-Guevara and Jara Vriese and Carlo Ferri Marini},
journal = {PeerJ},
year = {2026},
month = oct,
doi = {10.7717/peerj.21806},
url = {https://peerj.com/articles/21806},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Moderators of metabolic threshold adaptations: a systematic review and meta-analysis
AU - Ratko Peric
AU - Zoran Nikolovski
AU - Dario Vrdoljak
AU - Antonela Karmen Ivisic
AU - Isaac A Chavez-Guevara
AU - Jara Vriese
AU - Carlo Ferri Marini
PY - 2026
DA - 2026/10/22
JO - PeerJ
DO - 10.7717/peerj.21806
UR - https://peerj.com/articles/21806
AB - Optimal training intensity relative to individual metabolic thresholds remains ambiguous despite its fundamental importance in endurance sports. The present pre-registered systematic review and meta-analysis (PROSPERO: CRD420251020702) evaluated the relative influence of potential moderators on adaptations in the aerobic (AeT) and anaerobic (AnT) thresholds. The primary outcome variable was the magnitude of change in physiological threshold values from pre- to post-intervention, quantified through power output (W), speed (km/h), or oxygen uptake metrics (VO 2max ). Three-level meta-analytic models with cluster-robust variance estimation quantified Log Response Ratio effect sizes across 13 studies (24 intervention groups, 338 participants). Among the substantive moderators examined ( i.e. , training intensity, participant status, and intervention length), training intensity relative to the metabolic threshold showed the most consistent association with changes in threshold-related outcomes. For AeT ( k = 9), a significant effect of training intensity was observed ( p = 0.017), with supra-threshold training showing the largest improvement (+38.7%) compared with at-threshold (+14.7%) and sub-threshold (+18.4%) training. For AnT ( k = 15), a significant categorical effect of training intensity was observed ( p = 0.008), with post-hoc comparisons revealing greater adaptations for supra-threshold versus sub-threshold training ( p = 0.010), alongside a graded descriptive pattern across categories (below: +2.6%, at: ∼+7%, above: +12.2%). However, substantial heterogeneity persisted (AeT: I ² ≈ 89%; AnT: I ² ≈ 53%), likely reflecting threshold identification bias ( e.g. , lactate vs. gas analysis) and varying background training distributions. These findings identify training intensity as a primary moderator associated with threshold adaptations within the current literature, with supra-threshold metabolic range consistently outperforming at- or below-threshold prescriptions within the limited supra-threshold ranges represented in the included studies. Therefore, individualized, supra-threshold training with regular reassessment seems to be recommended to optimize individual training responses. However, substantial heterogeneity and methodological variability warrant caution, and further well-controlled studies are needed before definitive training recommendations can be made.
SN - 2167-8359
ER -