Abnormal performance of cervical stabilizer muscles in individuals with low back pain.

Objectives: To compare the performance of cervical stabilizer muscles using the craniocervical flexion test (CCFT) among individuals with subacute, chronic, and asymptomatic low back pain (LBP) conditions. Methods: Individuals with subacute (N = 23) and chronic LBP (N = 23) with their age- and gender-matched controls (N = 30) participated in this study. All recruited participants were required to perform the CCFT. The activation score (AS) and the performance index (PI) were recorded by an assessor who was blinded to the group of participants. Results: Approximately, 74% of subacute LBP participants and 60-65% of chronic LBP participants obtained abnormal AS and PI. AS was significantly lower in participants with subacute (P = 0.0002) and chronic LBP (P = 0.0009) than the control group. Likewise, the PI was significantly lower in participants with subacute (P = 0.0002) and chronic LBP (P = 0.0036) than the control group. Participants in the subacute LBP group showed significantly greater percentages of abnormal responses on the AS (P < 0.0001) and the PI (P = 0.0001) than the control. Discussion: Abnormal performance of cervical stabilizer muscles using the CCFT was demonstrated in a high proportion of participants with LBP. The findings highlight the plausible association in muscle control between cervical and lumbar stabilizers. Level of Evidence: 2b.

Effects of chronic low back pain, age and gender on vertical spinal creep.

This study investigated the effect of chronic low back pain, age, gender, and time of measurement on the magnitude of vertical spinal creep (VSC) and its recovery. A mixed design, involving three independent variables (chronic low back pain, age, and gender) and one repeated variable (time), was used. One hundred and six subjects of both genders, with and without chronic low back pain, aged between 20 and 60 years, participated in the study. The measurement of VSC and its recovery was performed using a seated stadiometer that allowed continuous measurement of VSC without changing the subject's posture over 25 min. Unloaded VSC was measured during the initial 5 min, followed by 10 min with an additional load of 15% of the subject's body weight and then for a further 10 min after the removal of the load. Subjects were grouped into one of eight categories according to the presence of chronic low back pain, age (20-39 years or 40-60 years) and gender. Repeated measures analysis of variance was computed. A significant increase in VSC with time of measurement was observed (p<0.001). No significant main effects for chronic low back pain, age, or gender were found at any time during the 25-min VSC testing protocol. Significant interactions were found between age and gender during the loaded (p=0.02) and unloaded (p=0.02) phases. A significant interaction was found between chronic low back pain and gender at the end of the unloaded phase (p=0.04). These findings suggest a combined influence of chronic low back pain, age, and gender on VSC and its recovery and that the dominance of each variable changed with the time of the measurement. Thus, subjects who differ in the presence of chronic low back pain, age, and gender should not be combined for statistical analysis of VSC and its recovery.

Reliability of the vertical spinal creep response measured in sitting (asymptomatic and low-back pain subjects).

Vertical spinal creep (or change in stature) has been used as an index of spinal loading, yet reliability of the testing protocol has not been fully examined. This study investigated the reliability of a vertical spinal creep response in 10 asymptomatic and five low-back pain subjects. Each subject performed the 25-min testing protocol, which consisted of three phases (5-min preload, 10-min loaded and 10-min unloaded), at the same time on two separate days. Good reliabilities in vertical spinal creep response between two days of testing were demonstrated for both asymptomatic and low-back pain subjects.

Contribution of soft tissue deformation below the sacrum to the measurement of total height loss in sitting.

This study investigated the contribution of soft tissue deformation below the sacrum (S) and vertical spinal creep to total height loss (THL) measured in sitting. Eight asymptomatic subjects (four males, four females) aged between 21 and 51 years were measured. Simultaneous measurement of THL and S were commenced after the subjects had been sitting for 5 min. THL was recorded while subjects were positioned in a seated stadiometer, which controlled their spinal posture. S was measured by placing an ultrasound transducer at the level of the top of the subject's sacrum. Over 25 min of sitting with loaded and unloaded interventions applied to their spine, different response characteristics between S and THL were noted. This study demonstrated that soft tissues below the sacrum could contribute up to 30% on average of total height loss. This suggests that researchers should take into account the soft tissue deformation outside the spine when studying vertical creep in sitting.

Adolescent versus adult responses to vertical spinal loading.

This study compared the vertical spinal creep response between adolescent and adult males. Thirty healthy male subjects, 15 adolescents (aged 12 to 16 years) and 15 adults (aged 30 to 57 years) were measured. Spinal creep was measured continuously over 25 min under loaded and unloaded conditions using a seated stadiometer that controlled spinal posture. Both adolescent and adult subjects showed significant increase in vertical spinal creep with time but the magnitude of vertical spinal creep was significantly greater in adolescent than in the adult subjects.