title: Shoulder manual muscle resistance test cannot fully detect muscle weakness.
abstract: OBJECTIVE
  The shoulder manual resistance test is one of the common clinical assessments for patients with muscle weakness. However, there have been no studies investigating the threshold for muscle weakness. The purpose of this study was to clarify the threshold for muscle weakness in the shoulder manual muscle resistance test.
  
  
  METHODS
  Fifty-three patients (37.9 ± 20.6 years old) with either rotator cuff tear (21 patients), superior labrum anterior-to-posterior (SLAP) lesion (7 patients), or Bankart lesion (25 patients) of one shoulder were administered three manual muscle resistance tests (abduction strength, external rotation, and belly press tests). Positive results in these tests were defined as a subjective weakness in the involved shoulder compared to the opposite shoulder. Based on this result, the patients were divided into positive and negative groups. Another observer measured isometric strength using a hand-held dynamometer and calculated the side-to-side ratio. Comparing instrument measurement with manual measurement, the cut-off point, at which we can recognise that there is a side-to-side difference, was calculated by receiver operating characteristic analysis.
  
  
  RESULTS
  The cases with less than 60% of the muscle strength in the contralateral shoulder were judged as positive in all examinations, whereas among the cases with 60-90% of muscle strength, there was a mixture of negative and positive determinations. The cut-off point was 78.9% in the abduction strength test, 73.8% in the external rotation test, and 84.0% in the belly press test.
  
  
  CONCLUSIONS
  The side-to-side difference could be manually detected, when muscle strength was less than 75-85% of that on the contralateral side. This finding suggests that it is necessary to understand the limitation of these manual tests in the case of clinical examinations. Therefore, care must be taken for the shoulder manual muscle resistance test as muscle weakness cannot be fully detected by manual measurement.
  
  
  METHODS
  Case-control study, Level IV.
authors.affiliation: Rehabilitation, JCHO Osaka Hospital, 4-2-78 Fukushima, Osaka City, Osaka, 553-0003, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nagatomi
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Mae
authors.affiliation: Rehabilitation, JCHO Osaka Hospital, 4-2-78 Fukushima, Osaka City, Osaka, 553-0003, Japan.
authors.forename: Teruyoshi
authors.initials: T
authors.lastname: Nagafuchi
authors.affiliation: Department of Orthopaedic Surgery, JCHO Hoshigaoka Medical Center, Hirakata, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Yamada
authors.affiliation: Department of Physical Therapy, Hyogo University of Health Sciences, Kobe, Japan.
authors.forename: Koutatsu
authors.initials: K
authors.lastname: Nagai
authors.affiliation: Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan. yonepy2796@gmail.com.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoneda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018908:Muscle Weakness / Q000175:diagnosis* / Q000503:physiopathology; D010808:Physical Examination; D011237:Predictive Value of Tests; D000070636:Rotator Cuff Injuries / Q000503:physiopathology*; D012785:Shoulder Joint / Q000503:physiopathology*; D055815:Young Adult
keywords: Abduction strength test; Belly press test; Cut-off point; External rotation test; Muscle weakness; Rotator cuff tear