Scoping Review · Sports Medicine · HIFT

Rise and Occasional Demise of the Hybrid Athlete

a scoping review of the musculoskeletal and broader health impacts of high-intensity functional training

PRISMA-ScR Scoping Review HIFT MSK Injury CrossFit & Functional Training
In-progress scoping review — findings subject to revision prior to final publication
60
Included studies
501
Records screened
12,261
Participants
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60
Included studies
501
Records screened
12,261
Participants
2014–24
Publication window
5
Databases
Collaborative institutions and partners Collaborative institutions and partners
David Munn · Lewis Turmeau · Ronan Kearney · Edel Fanning · Fearghal Kerin · Mark Jackson · Stuart O’Flanagan · Pieter D’Hooghe · Andrea Goceva · Alan Kourie · Andrew J Hall
STRIKERS Elite Sports Group, Dublin, Ireland · University of St Andrews, St Andrews, UK
The Review

Abstract

Background

High-intensity functional training (HIFT) has grown in popularity among the general population. HIFT approaches combine strength, endurance, and mixed-modality functional exercise. Despite increasing uptake, uncertainty remains regarding injury risk and the broader effects on physical and psychological health.

Objectives

Map the literature relating to HIFT and associated practices, examine injury risk and prevention strategies, and identify broader physiological, psychological, and societal health effects.

Design

PRISMA-ScR scoping review with descriptive and thematic synthesis. Peer-reviewed literature identified from Scopus, Web of Science, PubMed, ProQuest Central, and Ovid, limited to publications from 2014 to 2024.

Results

501 records were screened and 60 studies were included after full-text review. The literature was heterogeneous in design, populations, and terminology. Injury risk in HIFT did not appear uniformly greater than in traditional training approaches. Risk was multifactorial, more commonly linked to chronic loading and overuse than to isolated events. Prevention was strongly influenced by coaching quality, load management, and movement competency. These modalities were associated with favourable cardiometabolic adaptations, with psychological and wellbeing benefits an emerging but under-studied area.

Conclusions

Hybrid and high-intensity functional training present a mixed profile of risk and benefit, but the musculoskeletal risks identified are likely substantially outweighed by the wider physical, mental, and social benefits of exercise participation. Future research should prioritise clearer definitions, prospective injury surveillance, and standardised outcome reporting to better inform safe participation and athlete care.

Key Findings

What the literature shows

Across 60 included studies, several consistent themes emerged regarding injury risk, prevention, physiological adaptation, and broader health outcomes in HIFT populations.

Injury risk
Not uniformly elevated
Injury risk in HIFT did not appear uniformly greater than in traditional training approaches. Risk was multifactorial, more commonly linked to chronic loading and overuse mechanisms than to isolated acute events.
Prevention
Coaching, load, and movement
Prevention was strongly influenced by coaching quality, load management, and movement competency. Athletes from affiliated gyms demonstrated lower injury rates than those from non-affiliated facilities.
Physiological adaptation
Favourable cardiometabolic profile
HIFT modalities were associated with favourable cardiometabolic adaptations. Physiological adaptation was the most frequently studied outcome theme, represented across 26 of 60 included studies.
Psychological wellbeing
An under-studied area
Evidence for mental health and wellbeing benefits was emerging but limited to only 2 of 60 studies. This represents a significant gap given the visible social and community dimensions of HIFT participation.
Risk factors
Training load · Movement quality · Supervision and coaching · Chronic / overuse mechanisms · Systemic physiological demands
Prevention levers
Coaching quality · Load management · Movement competency
Literature characteristics
Descriptive sources predominate · Inconsistent terminology · Limited methodological comparability · Growing interest in field development
Evidence Profile

Study characteristics and evidence levels

Evidence levels were assessed using the Oxford Centre for Evidence-Based Medicine (CEBM) framework across 44 of the 60 included studies. The literature was predominantly observational.

Oxford CEBM Evidence Levels (n=44 rated studies)
Level 1 (Systematic reviews / RCTs) 4
Level 2 (Cohort studies) 11
Level 3 (Case-control / retrospective) 16
Level 4 (Case series) 9
Level 5 (Expert opinion) 4
Not yet rated 16
Outcome themes (studies may address more than one)
Physiological adaptation 26
Injury risk and prevention 18
Psychological and wellbeing 2
Totals do not sum to 60; individual studies may address multiple themes.
Risk & Benefit Synthesis

Weighing the evidence

HIFT presents a mixed but overall favourable risk-benefit profile. As a visible, accessible, and habit-forming exercise modality, HIFT may reduce barriers to participation and support sustained physical activity engagement.

Identified risks
  • Injury risk multifactorial; chronic/overuse mechanisms predominate
  • Higher rates in non-affiliated, less-supervised training environments
  • Prior injury is a significant risk factor for re-injury
  • Systemic physiological demands may exceed capacity in unprepared individuals
  • Literature base heterogeneous; true injury burden difficult to quantify
Identified benefits
  • Favourable cardiometabolic adaptations across multiple studies
  • Accessible, community-based exercise model with high participation rates
  • Emerging evidence for mental health and wellbeing benefits
  • Modality supports sustained physical activity engagement
  • Potential to reduce population-level barriers to exercise participation
"The musculoskeletal risks identified are likely substantially outweighed by the wider physical, mental, and social benefits of exercise participation. As visible, accessible, and habit-forming exercise modalities, HIFT approaches may reduce barriers to participation, support sustained engagement, and promote positive feedback loops around physical activity in society."

Research priorities

This study

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In-progress scoping review. Findings subject to revision prior to final publication.