Activity of Erector Spinae During Trunk Forward Bending and Backward Return: The Effects of Age

Lower back muscle activity during weight-shifting is affected by ageing and dual-tasking

PURPOSE

Postural control deteriorates with age, especially under dual-task conditions. It is currently unknown how a challenging virtual reality weight-shifting task affects lower back muscle activity. Hence, this study investigated erector spinae neuromuscular control during mediolateral weight-shifting as part of an exergame during single- (ST) and dual-task (DT) conditions in young and older adults.

METHODS

Seventeen young and 17 older adults performed mediolateral weight-shifts while hitting virtual wasps in a virtual environment with and without a serial subtraction task (DT). Center of mass position was recorded in real-time using 3D motion capturing. Electromyography recorded bilateral activation of the lumbar longissimus and iliocostalis muscles.

RESULTS

Weight-shifting (p < 0.03) and targeting the wasps (p < 0.005) deteriorated with age and DT. Relative muscle activation during both quiet stance and weight-shifting increased with age, while the DT-effect did not differ consistently between age-groups. However, bilateral muscle co-contraction decreased with DT in young adults only. When switching direction and targeting the wasps, variability of muscle activation increased with age and DT and proved related to worse targeting performance. These effects were mainly visible at the non-dominant body side.

CONCLUSION

Older adults showed a higher erector spinae muscle contribution to perform weight-shifts with increased variability at the end of a shift, whereby muscle activity was modulated less well in older than in young adults in response to DT. Hence, the current findings point to the potential for developing postural training in which older adults learn to fine-tune trunk muscle activity to improve weight-shifting and reduce fall risk.

Effects of Pelvic-Tilt Imbalance on Disability, Muscle Performance, and Range of Motion in Office Workers with Non-Specific Low-Back Pain

Imbalance in the pelvic tilt is considered to be a major variable in low back pain. The purpose of this study was to investigate the effects of pelvic-tilt imbalance on trunk- and hip-muscle performance, range of motion, low-back pain, and the degree of disability in office workers. This was a cross-sectional study conducted in a physical therapy clinic on forty-one office workers diagnosed with non-specific low-back pain. Among the office workers with non-specific low-back pain, 25 were assigned to the pelvic-tilt-imbalance group and 16 to the normal group without pelvic-tilt imbalance. In order to determine the differences according to the imbalance in pelvic tilt, the pain intensity and disability indices were compared between the groups. In addition, the muscle performance and range of motion of the trunk and hip joints and foot pressure were measured and compared. There were differences between the groups in the disability indices and the ratio of internal and external rotation of the hip joint. However, there were no differences in the other variables. Pelvic-tilt imbalance in office workers with non-specific chronic low-back pain may exacerbate the degree of disability and be related to hip-joint rotational range of motion.

Association between endurance of the trunk extensor muscles and balance performance in community-dwelling older adults: a cross-sectional analysis

Background/Aims

Previous research has disregarded the performance of the extensor muscle group of the trunk in balance control. The main purpose of this exploratory study was to assess the association between balance performance and endurance of the trunk extensor muscles in older adults, considering possible co-factors such as age and body mass index.

Methods

A correlational and predictive cross-sectional study was conducted with 61 community dwelling older adults (women n=45) with a mean age of 71 years (± standard deviation 6 years), and a mean body mass index of 28.1 kg/m2 (± standard deviation ± 4.7 kg/m2). The Berg Balance Scale was used to assess balance performance and Trunk Extensor Endurance Test to assess muscle endurance. Spearman's correlation coefficients (ρ) and single and multiple regression analyses were performed. Statistical significance was set at 0.05.

Results

The largest correlations were found between the Berg Balance Scale score and Trunk Extensor Endurance Test (ρ=0.41, P=0.001) and body mass index (ρ=−0.36, P=0.005). Muscle endurance alone predicted ~10% of the Berg Balance Scale score (R2=0.10, P=0.015). When combined with body mass index, it accounted for ~19% (R2=0.19, P=0.002). Adding the remaining variable (age) to the previous model increased the prediction by ~3% (R2=0.22, P=0.002).

Conclusions

Muscle endurance and body mass index significantly predicted (~19%) balance performance in older adults. Because these are modifiable factors, they should be routinely included in the screening of balance performance in older adults and addressed accordingly in preventive or rehabilitation programmes.

Older Compared With Younger Adults Performed 467 Fewer Sit-to-Stand Trials, Accompanied by Small Changes in Muscle Activation and Voluntary Force

Background: Repetitive sit-to-stand (rSTS) is a fatigue perturbation model to examine the age-effects on adaptability in posture and gait, yet the age-effects on muscle activation during rSTS per se are unclear. We examined the effects of age and exhaustive rSTS on muscle activation magnitude, onset, and duration during ascent and descent phases of the STS task.

Methods: Healthy older (n = 12) and younger (n = 11) adults performed rSTS, at a controlled frequency dictated by a metronome (2 s for cycle), to failure or for 30 min. We assessed muscle activation magnitude, onset, and duration of plantar flexors, dorsiflexors, knee flexors, knee extensors, and hip stabilizers during the initial and late stages of rSTS. Before and after rSTS, we measured maximal voluntary isometric knee extension force, and rate of perceived exertion, which was also recorded during rSTS task.

Results: Older vs. younger adults generated 35% lower maximum voluntary isometric knee extension force. During the initial stage of rSTS, older vs. younger adults activated the dorsiflexor 60% higher, all 5 muscle groups 37% longer, and the hip stabilizers 80% earlier. Older vs. younger adults completed 467 fewer STS trials and, at failure, their rate of perceived exertion was ~17 of 20 on the Borg scale. At the end of the rSTS, maximum voluntary isometric knee extension force decreased 16% similarly in older and younger, as well as the similar age groups decline in activation of the dorsiflexor and knee extensor muscles (all p < 0.05).

Conclusion: By performing 467 fewer STS trials, older adults minimized the potential effects of fatigability on muscle activation, voluntary force, and motor function. Such a sparing effect may explain the minimal changes in gait after rSTS reported in previous studies, suggesting a limited scope of this perturbation model to probe age-effects on muscle adaptation in functional tasks.

Correlation between non-specific chronic low back pain and physical factors of lumbar and hip joint in office workers

OBJECTIVE

The purpose of this study was to investigate the correlation between pain intensity, degree of disability, and various physical variables of the lumbar and hip joints in office workers with non-specific chronic low back pain.

STUDY DESIGN/SETTING

A cross-sectional correlational study/in-house physical therapy clinic.

SUBJECTS

Sixty-one office workers diagnosed with non-specific chronic low back pain.

METHODS

Pain intensity and Oswestry disability index were surveyed, and lumbar flexor and extensor strength ratio, lumbar flexor and extensor endurance, the maximum value and left/right asymmetry of eccentric muscle activity of the lumbar extensor, the maximum value and left/right asymmetry of concentric muscle activity of the lumbar extensor, the ROM of lumbar flexion and extension, left/right asymmetry of hip joint extensor strength, the internal rotation and external rotation of the hip joint, and the ROM and left/right asymmetry of flexion and extension were measured.

RESULTS

The ratio of the muscle strength of lumbar flexor and extensor was in a weak correlation with disability index. In addition, hip joint ROM and left/right asymmetry of hip joint ROM correlate with pain intensity and disability index.

CONCLUSION

To improve office workers' pain intensity and disability due to this non-specific chronic low back pain, it may be important to improve the ratio of the lumbar extensor and flexor strength and the left/right asymmetry of the hip joint ROM as well as the ROM of the hip joint should be considered.