This study evaluated lumbar spine muscle volume and Muscle Fatty Infiltrate (MFI) across two age groups of healthy adults. Twenty-four participants (young group - YG: age 18-25, n = 12; mature group - MG: age 45-60, n = 12) without low back pain underwent T1-weighted axial MRI. Muscle volume and MFI were obtained from the left and right lumbar erector spinae (ES), multifidus (M), rectus abdominis (RA) and psoas (PS) muscles. For MFI, mean pixel intensity (MPI) of muscles was reported as a percentage of subcutaneous fat MPI. Within-group comparison of left and right side muscle volume was not significantly different in the YG. In the MG, right RA and ES were significantly smaller than left (RA p = 0.049; ES p = 0.03). In both groups, left PS, M and ES MFI was significantly smaller compared to the right side and left RA MFI was significantly greater compared to right side (all p ≤ 0.001). For M volume, 81.7-84.6% of variance was explained by age, height and Body Mass Index (BMI). For ES volume, 81.6-82.8% of variance was explained by height and BMI. Age explained 18.1%-36.0% of variance in M and ES right MFI. Therefore, age and BMI are relevant factors for extensor muscle volume, but not for flexor muscle volume. Also, age significantly influences MFI for right-sided extensors only. The age effect is apparently independent of full subjective back functionality. For future spinal muscle research, the side-and muscle-specific effect of age on muscle morphology should be considered.

More experienced runners have a lower rate of injury. A novice runner should use a recognised structured training programme. These results suggest that graduated loading is important for novice runners, and that load modification may be important whilst recovering from an injury, however full recovery from previous injury may prevent future injury.

BackgroundThe spinal column including its vertebrae and disks has been well examined and extensively reported in relation to age-aggregated degeneration. In contrast, paravertebral muscles are poorly represented in describing normative degeneration. Increasing evidence points to the importance of paravertebral muscle quality in low back health, and their potential as a modifiable factor in low back pain (LBP). Studies examining normative decline of paravertebral muscles are needed to advance the field’s etiological understanding. With a novel approach and based on published data, we establish and compare decline rates of imaging features for degeneration of lumbar vertebrae and disks, versus fatty infiltration in paravertebral muscles in asymptomatic adults.MethodsOur cross-sectional simulation study examined age-aggregated data from three published studies who reported on asymptomatic adults spanning 18–60 years. Prevalence rates of imaging degenerative features of the spinal column were examined via logistic regression and compared with percentage fatty infiltration in erector spinae, multifidus and psoas using synthetic data and Monte Carlo simulation with 10,000 endpoint-specific regression iterations. General linear regression models were employed to estimate marginal effects of age reported as a one-year change rate (with 95 % confidence intervals) for comparisons between all reported spinal features.ResultsDeclines in multifidus (0.24 & 0.11 %/year), erector spinae (0.13 & 0.07 %/year), and psoas (0.04 %/year) occur at similarly slow rates to disk protrusion (0.25 %/year), annular fissure (0.15 %/year), and spondylolisthesis (0.29 %/year). Multifidus showed a trend for faster decline than erector spinae, particularly in men. Of the features examined, disk signal loss declined fastest, and psoas muscle the slowest.ConclusionsDegeneration of lumbar paravertebral muscles occurs slowly in asymptomatic adults, with a tendency to be most pronounced in multifidus. Rate of decline of spinal structures represents a novel variable that warrants inclusion as a known feature of the expected degenerative cascade, and to provide a basis for comparison to diseases of the spine in research and clinical practice. Concurrent examination of spinal features using advanced imaging to improve muscle analysis would be a strong addition to the field.

IntroductionMagnetic resonance imaging (MRI) is frequently used to quantify and determine any association between muscle morphology and neuromusculoskeletal pathology or dysfunction through the evaluation of muscle cross-sectional area (CSA) (1,2,3,4,5,6,7) and muscle fatty infiltrate (MFI) (5,8,9,10,11,12). These parameters of muscle morphology are also often investigated to identify expected age-related muscle changes (13,14).Many, though not all, studies analysing spinal muscle CSA and MFI report intra-and/or inter-rater reliability as part of their investigations (4,5,7,15,16), many of which demonstrate strong intra-rater reliability of lumbar erector spinae and multifidus CSA, with an intraclass correlation (ICC) ranging from 0.85 (5, 15) to 0.98 (4) and an inter-rater reliability ranging from 0.77 (7) to 0.85 (5). However, the specific reporting of intra-and/or inter-rater reliability findings is often lacking regarding the description of the methodology of assessor agreement and assessor experience. Further, most studies have published a global muscle CSA ICC for intra-rater reliability by reporting a single value, rather than distinguishing between the right and left sides. Battié and colleagues (17) have, however, detailed lumbar paraspinal muscle volume ICC for both the left and the right sides to range from 0.90 to 0.99 in patients with lumbar radiculopathy. Published inter-and intra-rater reliability outcomes of other trunk muscles have been noticeably limited, although one study Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts was identified to report a global intra-rater reliability of the psoas muscle CSA, which was found to be high with an ICC of 0.92 (15).Intra-and inter-rater reliability of MFI is less frequently reported in the literature compared to muscle CSA. In addition, due to the range of MFI quantification methods, MFI intra-and inter-rater reliability findings may not be easily compared across studies. Using opposedphase MRI, intra-rater reliability of lumbar multifidus and erector spinae MFI was found to be high in patients with persistent low back pain, with an ICC range of 0.86 to 0.88 (5). This study also found an equally high inter-rater reliability (ICC 0.85 -0.87) for MFI in these muscles.Although the inter-rater reliability of generalised lumbar extensor muscle CSA has been identified, the reporting of inter-and intra-reliability metrics for the left and right sides of individual muscle CSA and MFI is infrequent. Furthermore, reports for other trunk muscles, such as the abdominals are, to our knowledge, lacking. Therefore, the purpose of this study was to identify an inter-rater reliability metric for the quantification of the left and right individual lumbar spine and abdominal muscle volume and MFI between two novice assessors. Materials and Methods ParticipantsAxial MRI scans of 10 healthy male participants from a University population who were recruited as part of a larger study were included. Data collectionTransverse T1-weighted magnetic resona...

The study of muscle activity using surface electromyography (sEMG) is commonly used for investigations of the neuromuscular system in man. Although sEMG has faced methodological challenges, considerable technical advances have been made in the last few decades. Similarly, the field of animal biomechanics, including sEMG, has grown despite being confronted with often complex experimental conditions. In human sEMG research, standardised protocols have been developed, however these are lacking in animal sEMG. Before standards can be proposed in this population group, the existing research in animal sEMG should be collated and evaluated. Therefore the aim of this review is to systematically identify and summarise the literature in animal sEMG focussing on (1) species, breeds, activities and muscles investigated, and (2) electrode placement and normalisation methods used. The databases PubMed, Web of Science, Scopus, and Vetmed Resource were searched systematically for sEMG studies in animals and 38 articles were included in the final review. Data on methodological quality was collected and summarised. The findings from this systematic review indicate the divergence in animal sEMG methodology and as a result, future steps required to develop standardisation in animal sEMG are proposed.

Background Chronic low back pain (CLBP) is the most prevalent musculoskeletal disorder. Aquatic exercises are commonly used by physical therapists for CLBP treatment and management; however, there are no data on trunk muscle activation during aquatic exercises in people with CLBP. Objective We quantified activation of trunk and gluteal muscles, exercise intensity, pain, and perceived exertion in people with and without CLBP when performing water and land exercises. Design The study used a cross-sectional design. Methods Twenty participants with nonspecific CLBP and 20 healthy participants performed 15 aquatic exercises and 15 similar land exercises. Mean and peak muscle activation were measured bilaterally from erector spinae, multifidus, gluteus maximus, gluteus medius, rectus abdominis, external oblique, and internal oblique using waterproof and wireless surface electromyography. Exercise intensity (heart rate), perceived exertion (Borg scale), and, for the CLBP group, pain (visual analog scale) were recorded. Results There were no significant between-group differences. Significant between-environment differences were found in heart rate (always higher on land), exertion (higher in the water for 3 exercises and on land for 6 exercises), and muscle activation (higher on land in 29% and in the water in 5% of comparisons). Pain levels were low, but pain was reported more than twice as frequently on land than in water (7.7% vs 3.7%, respectively). Limitations People with high levels of disability and CLBP classification were not included. Conclusions People with mild-to-moderate CLBP had similar exercise responses to healthy controls. Aquatic exercise produced sufficient muscle activation, intensity, and exertion, and should not be assumed to be less strenuous or less effective in activating trunk and pelvic muscles than exercise on land. These data can be used to inform design and prescription of rehabilitation programs and interventions.

Background Most research into the health benefits of human-animal interaction has focused on species that interact physically with humans, such as dogs. This may be unsuitable for certain populations for reasons including accessibility and the risk of negative consequences to both the person and the animal. However, some research has associated viewing fish in aquariums with positive well-being outcomes; as there is no physical contact with the animal, this form of interaction carries less risk. At present, little is known about the specific benefits of human-fish interaction. Objectives To explore current evidence relating to the psychological and physiological benefits of interacting with fish in aquariums. Methods Systematic searches were conducted to identify relevant primary research of any design. All forms of interaction were considered, including keeping fish as companion animals and fish aquarium-based interventions. “Non-live” alternatives, such as videos, were also considered. This review was conducted according to a registered protocol (PROSPERO ID: CRD42018090466). Results Nineteen studies were included. Two provided tentative evidence that keeping home aquaria is associated with relaxation. The remaining studies involved novel interactions with fish in home or public aquariums. Outcomes relating to anxiety, relaxation and/or physiological stress were commonly assessed; evidence was mixed with both positive and null findings. Preliminary support was found for effects on mood, pain, nutritional intake and body weight, but not loneliness. All studies had methodological issues and risk of bias was either high or unclear. Conclusions Review findings suggest that interacting with fish in aquariums has the potential to benefit human well-being, although research on this topic is currently limited. Future research should aim to address gaps in the evidence, such as whether and how the type of human-fish interaction can influence well-being outcomes. Researchers should also aim to address the methodological concerns highlighted in this review.

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