Table 3 Characteristics of 8 studies examining the concurrent validity of MMT

Bohannon ⁹⁵ (2001)

128 acute knee rehabilitation patients

physical therapist

To compare MMT with hand-held dynamometer measurements of knee extension strength

MMT and dynamometer scores highly correlated (r = 0.768; P < 0.001). Convergent and construct validity of MMT and dynamometry measurements demonstrated.

Caruso and Leisman³⁶ (2000)

27 volunteers with no knowledge about MMT or AK

2 examiners

To show the difference between "weak" and "strong" muscles, using MMT and dynamometer testing

Study showed that examiners with over 5 years experience using AK had reliability and reproducibility when their outcomes were compared. Perception of "inhibition" or weakness made by examiner was corroborated by test pressure analysis using the dynamometer.

Lawson and Calderon ⁴⁸ (1997) **

30 asymptomatic volunteers

Medical doctor

10 upper extremity muscles were tested using AK methods in double-blind conditions.

MMTs of "weak" or "strong" muscles showed significantly different electromyographic measurements and demonstrated a high correlation between testing methods.

Schwartz et al ⁹⁶ (1992)

122 patients with spinal cord injuries at C4–C6

physical therapists

Relationship between MMT and hand-head myometry compared

Sequential examinations with MMT and myometry were made at 72 hours, 1 week, and 2 weeks post-spinal cord injury and at 1, 2, 3, 4, 6, 12, 18, and 24 months post-injury. Results showed that 22 of 24 correlations between MMT and myometry were significant at p values less than .001.

Perot et al ⁵⁷ (1991)

10 subjects

Chiropractors

To measure and compare both electromyographic and MMT results after proprioceptive techniques to both strengthen and weaken muscles

Response of tibialis anterior muscle to proprioceptive technique showed a significant EMG difference that corresponded to the difference found between "strong" and "weak" MMT outcomes. AK proprioceptive procedure to reduce muscle tone found to correlate with MMT outcomes.

Hsieh and Phillips ⁴⁶ (1990)

15 asymptomatic subjects

3 chiropractors

To determine the concurrent validity of manual dynamometry using AK style of MMT, comparing doctor-initiated and patient-initiated MMT

Intratester reliability and correlation coefficients for testers 1, 2, and 3 were 0.55, 0.75, and 0.76 with doctor-initiated method; 0.96, 0.99, and 0.97 when patient-initiated MMT method. The intertester reliability coefficients were 0.77 and 0.59 on day 1 and 2 respectively for doctor-initiated method; and 0.95 and 0.96 for the patient-initiated method.

Wadsworth et al ⁴⁵ (1987)

5 muscle groups on 11 patients

physical therapist

To compare the concurrent reliability of MMT and hand-held dynamometer tests

The correlation coefficients were high and significantly different from zero for four muscle groups tested dynametrically and for two muscle groups tested manually. The test-retest reliability coefficients for two muscle groups tested manually could not be calculated because the values between subjects were identical. Conclusion that both MMT and dynamometry are reliable testing methods, given the conditions described in this study.

Bohannon ⁹⁷ (1986)

50 patients

physical therapist

To determine the relationship between MMT word scores and dynamometer force scores using Kendall tau.

MMT scores and dynamometer test scores were significantly correlated (p less than 0.001). Percentage MMT and dynamometer test scores were significantly different (p less than 0.001). These results suggest that the two procedures measure the same variable-strength.

Marino et al ⁵⁰ (1982)

128 patients

physical therapists

To compare MMT findings with hand-held dynamometer (HHD) findings, with precise repetition of the MMT

The MMT and HHD values were within 5% of each other. The average hip abduction and hip flexion scores measured by the HHD were consistent with the examiner's perception of muscle weakness (P less than 0.001).

Triano and Davis ⁹⁸ (1976)

10 patients with "reactive muscle" phenomena described in AK

chiropractor

In patients with reactive muscle pairs (between the rhomboid and deltoid muscles), EMG and MMT findings were compared.

Study demonstrated that the reactive muscle phenomenon is, in fact, a physiologic imbalance of muscle measurable by EMG and MMT and was not a psychologic suggestion or an overpowering of the tested arm by brute force. These data showed that the deltoid-rhomboid "reactive muscle" represents a real physiological phenomenon.