Empirical Validation Using MAI Motion
The 3-Repetition
Squat Protocol.
The squat is biomechanically rich but physically demanding. This study asked how few repetitions are enough — and found that three carry the same kinematic signal as five, with marginally less variability.
10
Adult Participants
5 → 3
Repetitions
52
Parameters Compared
Why This Study Was Needed
How many repetitions is enough?
The five-repetition squat is commonly adopted for its balance between practicality and sensitivity in detecting functional deficits. But there is limited evidence defining the minimum number of repetitions needed for reliable kinematic measurement — and in practice, many people with chronic musculoskeletal conditions cannot complete five because of pain, fatigue or movement limitation.
Too few repetitions may compromise measurement stability; too many reduce feasibility in exactly the populations that need assessing.
Seven categories measured
Four parameters within each
Impulse (+ve and −ve)
The speed of change — degrees per second for joint angles and abduction, metres per second for left/right and core movement.
Impulse ratio
Positive impulse divided by negative impulse, reported as a unitless value.
Range of motion
Degrees for joint angles and abduction, metres for left/right and core movement.
Headline Finding
Three squats are enough.
Ten adults each performed five consecutive squats, recorded on a standard 1920×1080 RGB camera at 30 frames per second. Every participant’s first three repetitions were then analysed as a separate subset of the same recording — so the two protocols are compared within the same session, on the same movement.
5-Rep Protocol
Conventional Standard
100% of repetitions · mean CV 16.73% · greater fatigue burden
3-Rep Protocol
Comparable Output
60% of repetitions · mean CV 15.64% · no significant difference in means
Finding 01
No significant difference in means
Across every parameter, means derived from three repetitions matched those from five — with no statistically significant differences by one-way ANOVA with multiple comparisons.
Finding 02
Differences in means under 10%
All mean DiMs fell below 10%, with most parameters between 0% and 10%. Individual values reached 30% in a few cases, most notably impulse ratio in knee angle, ankle angle and hip abduction.
Finding 03
Three reps were slightly more consistent
The mean coefficient of variation across parameters was modestly but significantly lower at three repetitions than five — 15.64 ± 7.02 versus 16.73 ± 7.27 (p < 0.0001).
The Variability Result
Fewer reps, less noise.
Coefficient of variation was the study’s measure of consistency — under 10% is considered ideal, 10–20% acceptable. Most values sat in that acceptable band for both protocols. Where individual CVs ran high, around 60–70%, they ran high in both the five-rep and three-rep data, pointing to the participant rather than the protocol.
| Mean CV (%) | 5 Reps | 3 Reps | Result |
|---|---|---|---|
| All parameters, all participants | 16.73 ± 7.27 | 15.64 ± 7.02 | p < 0.0001 — lower at 3× |
| Participant 2 | 18.69 ± 12.72 | 14.91 ± 10.73 | p < 0.025 — lower at 3× |
| Participant 7 | 20.13 ± 13.51 | 17.07 ± 14.54 | p < 0.025 — lower at 3× |
| Participant 6 | 15.44 ± 11.29 | 18.03 ± 12.91 | p < 0.002 — lower at 5× |
Values are mean coefficient of variation ± standard deviation. Only three of the ten participants showed a statistically significant difference between protocols, and in two of those three the three-rep protocol was the more consistent.
The likely explanation
The authors suggest this reflects fatigue across the fourth and fifth repetitions — producing greater variability in neuromuscular control, posture and movement. Beyond a modest number of repetitions, additional cycles yield diminishing returns on measurement precision. They are explicit that formally establishing this would require further analysis.
Why It Matters Clinically
A test more people can actually finish.
The squat indicates lower limb strength, functional capacity and falls risk — all critical to maintaining independence. But its value depends on people being able to complete it. Participants in this study reported that three repetitions required less effort than five.
Combined with remote assessment on a standard camera, a shorter protocol makes measurement less demanding and more inclusive for people who are frail, in pain, or mid-rehabilitation.
Faster
Assessments
Fewer repetitions per participant improves time efficiency in clinic and research settings alike.
Reduced
Participant Burden
Participants reported that three repetitions required less effort than five.
Better
Protocol Adherence
A shorter protocol is more realistic for people who cannot complete five repetitions in one session.
Broader
Inclusion
Particularly relevant for elderly or frail individuals, where fatigue or discomfort limits feasibility.
What This Study Does Not Show
A pilot, described as preliminary.
A small pilot cohort
Ten participants — seven male, three female, mean age 60 ± 10.5 years, range 42 to 73. The authors describe the study as a pilot evaluation whose findings are preliminary.
Limited cohort diversity
The paper names limited diversity within the cohort as a constraint, and calls for validation in larger, more diverse populations.
One functional task
Only the squat was analysed. The authors propose including other functional tasks, such as single-leg stance, in future work.
Healthy participants only
Inclusion required the ability to safely complete five consecutive repetitions — so the very patients a shorter protocol would most help were, by design, not in the sample.
This study is the squat counterpart to the three-repetition sit-to-stand validation, and both feed the protocol design used across the MAI Motion programme — including the UniReliever® brace study, which measured both tasks.
A pragmatic standard for most populations.
Reducing repetition from five to three improves time efficiency, reduces participant burden and enhances protocol adherence — without measurable loss of kinematic signal.
Study Identity
- Authors:
- Tanvi Verma · Mathew George · Yan Wen · Paul Lee
- Institutions:
- MSK Doctors and Associates, Grantham · MSK Doctors, Sleaford · University of Leicester
- Journal:
- Cureus 18(8), published 27 August 2026
- Article:
- e115292
- Conduct:
- MSK House, Silk Willoughby, Sleaford, in accordance with ICH-GCP E6(R2)
- Licence:
- Creative Commons Attribution 4.0
Citation
Verma T, George M, Wen Y, Lee P. Empirical Validation of a Streamlined Three-Repetition Squat Protocol Using MAI Motion. Cureus. 2026;18(8):e115292. doi:10.7759/cureus.115292
The authors declare no financial support was received for the submitted work and no competing financial relationships.