Impact of the deep squat on articular knee joint structures, friend or enemy? A scoping review

Abstract

Background: The squat exercise has been shown to improve athletic performance. However, the use of the deep squat has been questioned due to claims that it may cause knee joint injuries. Therefore, the purpose of this scoping review was to synthesize existing literature concerning the impact of deep squats on knee osteoarticular health in resistance-trained individuals.

Methods: This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) guidelines. The original protocol was prospectively registered in Figshare (https://doi.org/10.6084/m9.figshare.24945033.v1). A systematic and exhaustive search was conducted in different databases: PubMed, Scopus, Web of Science, and SPORTDiscus. Additional searches were performed in Google Scholar and PEDro. The main inclusion criteria were the following: (1) Articles of experimental, observational, or theoretical nature, including randomized controlled trials, longitudinal studies, case reports, integrative reviews, systematic reviews, and meta-analyses(Primary studies were required to have a minimum follow-up duration of 6 weeks, whereas secondary studies were expected to adhere to PRISMA or COCHRANE guidelines or be registered with PROSPERO; (2) Peer-reviewed articles published between 2000 and 2024; (3) Publications written in English, Spanish and Portuguese; (4) Studies reporting the effects of deep half, parallel or quarter squats on the knee or evaluating squats as a predictor of injury.

Results: The keyword search resulted in 2,274 studies, out of which 15 met all inclusion criteria. These 15 studies comprised 5 cohort studies, 3 randomized controlled trials, 4 literature or narrative reviews, 1 case study, and 2 systematic reviews, one including a meta-analysis. Overall, the risk of bias (ROB) across these studies was generally low. It is worth noting that only one study, a case study, associated deep squats with an increased risk of injury, the remaining 14 studies showed no negative impact of deep squats on knee joint health.

Conclusion: The deep squat appears to be a safe exercise for knee joint health and could be included in resistance training programs without risk, provided that proper technique is maintained.

Keywords: injury; muscle strength; osteoarticular health; physical performance; range of movement; resistance training; sport-related actions.

Figure 1

PRISMA flow diagram representing the flow of information through the different phases of the scoping review.

Figure 2

Assessment of risk of bias in the case study included in the review.

Figure 3

Assessment of risk of bias in the cohort studies included in the review.

Figure 4

Assessment of risk of bias in the randomized controlled trials included in the review.

Figure 5

Assessment of risk of bias in the narrative reviews included in the review.

Figure 6

Assessment of risk of bias in the systematic reviews included in the review.

Figure 7

Representation of bibliometric analysis showing an overlay display of “keyword co-occurrence”. The size of the nodes represents the number of co-occurrences of the keywords in the articles and the color represents the date of publication. The connections between the nodes illustrate the degree of bibliographic reference in common among publications (https://www.vosviewer.com accessed January 06, 2024).

Figure 8

Representation of bibliometric analysis showing a network map of “co-citation of authors”. The size of the nodes represents the number of citations of the authors in the articles, and the color illustrates the degree of strength of association between authors (https://www.vosviewer.com retrieved January 06, 2024).