Effects of Training and Overtraining on Intervertebral Disc Proteoglycans

Impact of Running Exercise on Intervertebral Disc: A Systematic Review

CONTEXT

Running is one of the most popular sports worldwide. However, controversies exist regarding how running affects runner's intervertebral discs (IVD).

OBJECTIVE

The purpose of this study was to systematically review studies that evaluated IVD morphology or composition changes in response to running exercise, to determine the impact of running exercise on IVD.

DATA SOURCES

A systematic literature search was performed for 4 major databases: PubMed, Cochrane, Embase, and Web of Science.

STUDY SELECTION

Inclusion criteria were as follows: (1) healthy people without known IVD disease or major complications such as tuberculosis (IVD degeneration or low back pain are considered as minor complications); (2) subjects performed 1-time or regular running exercises; (3) pre and post comparison of runners or comparison between runners and healthy control subjects; (4) direct or indirect IVD morphology or composition measured; (5) IVD assessed before and after either acute or chronic running exercise, or compared cross-sectionally between runners and controls. Exclusion criteria were as follows: (1) reviews, editorials, letters or abstracts only; (2) animal studies; (3) subjects performed exercise other than running.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

The extracted data included study design and primary outcomes of the included studies. The Newcastle-Ottawa scale (NOS) was used to evaluate study quality and risk of bias.

RESULTS

A total of 13 studies with 632 participants were included in the final analysis; 4 studies measured IVD changes using stature or spinal height, and the other 9 measured IVD changes using magnetic resonance imaging; 6 studies found that running acutely and negatively impacts IVD; 3 out of 5 cross-sectional studies found that IVD parameters are better for runners than controls; 1 longitudinal study found no significant difference in IVD before and after training for marathon in runners; 1 longitudinal study found no significant difference in changes of IVD between runners and controls after 15 years of follow-up.

CONCLUSION

Negative changes in IVD exist for a short period of time after running, which may be due to the temporary compression pushing water content out of the disc. Cross-sectional studies suggest that long-term running exerts a mild positive effect on IVD; however, this inference has not been confirmed by high-quality longitudinal studies.

Causal association of physical activity with low back pain, intervertebral disc degeneration and sciatica: a two-sample mendelian randomization analysis study

Objective: Previous studies are insufficient to confirm a causal association between physical activity (PA) and low back pain (LBP), intervertebral disc degeneration (IDD), and sciatica. The present study used a two-sample Mendelian randomization (MR) analysis method to demonstrate whether or not there was a causal connection. Methods: First, four PA phenotypes were selected [accelerometer-based PA (average acceleration), accelerometer-based PA (acceleration fraction >425 mg), self-reported moderate-to-vigorous PA, and self-reported vigorous PA], setting thresholds for single nucleotide polymorphisms (SNPs) significantly concerned with PA p < 5 × 10-8, linkage disequilibrium (LD) r 2 < 0.01, genetic distance >5,000 kb, and F-value >10. SNPs associated with the outcome and confounding factors were then excluded using the PhenoScanncer database. Finally, after coordinating the genetic instruments from genome-wide association studies (GWAS) effect alleles for exposure and outcomes, multiplicative random effects inverse variance weighting (IVW), MR-Egger, weighted median method (WMM), and weighted mode method were used to assess exposure-outcome causality and perform sensitivity analysis on the estimated results. Results: The current study's IVW findings revealed proof of a causal connection between PA and LBP. While there was a positive causal tie between accelerometer-based PA (acceleration fraction >425 mg) and LBP [OR: 1.818, 95% CI:1.129-2.926, p = 0.012], there was a negative causal link between accelerometer-based PA (average acceleration) and LBP [OR: 0.945, 95% CI: 0.909-0.984, p = 0.005]. However causal relationship between PA and IDD or sciatica was not found. Conclusion: Increasing average PA but needing to avoid high-intensity PA may be an effective means of preventing low back pain. Although PA is not directly causally related to disc degeneration and sciatica, it can act through indirect pathways.

Hepatic Metabolic Profiling of Lifelong Exercise Training Rats

Regular physical exercise has been investigated as a primary preventive measure of several chronic diseases and premature death. Moreover, it has been shown to synchronize responses across multiple organs. In particular, hepatic tissue has proven to be a descriptive matrix to monitor the effect of physical activity. In this study, we performed an untargeted metabolomics-based analysis of hepatic tissue extracts from rats that have undergone either lifelong or chronic exercise training. For this purpose, 56 hepatic samples were collected and were analyzed by UHPLC-TOF-MS in negative ionization mode. This approach involved untargeted metabolite detection on hepatic tissue extracts accompanied by an in-house retention time/accurate mass library enabling confident metabolite identification. Unsupervised (PCA) and supervised (OPLS-DA) multivariate analysis showed significant metabolic perturbation on a panel of 28 metabolites, including amino acids, vitamins, nucleotides, and sugars. The training regime employed in this study resulted in a probable acceleration of the bioenergetic processes (glycolysis, glycogen metabolism), promoted catabolism of purines, and supplied biosynthetic precursors via the pentose phosphate pathway and pentose and glucuronate interconversions. Overall, the applied methodology was able to discriminate the different training schedules based on the rat liver metabolome.

Imaging of exercise-induced spinal remodeling in elite rowers

OBJECTIVES

As in-vivo knowledge of training-induced remodeling of intervertebral discs (IVD) is scarce, this study assessed how lumbar IVDs change as a function of long-term training in elite athletes and age-matched controls using compositional Magnetic Resonance Imaging (MRI).

DESIGN

Prospective case-control study.

METHODS

Prospectively, lumbar spines of 17 elite rowers (ERs) of the German national rowing team (mean age: 23.9 ± 3.3 years) were imaged on a clinical 3.0 T MRI scanner. ERs were imaged twice during the annual training cycle, i.e., at training intensive preseason preparations (t₀) and 6 months later during post-competition recovery (t₁). Controls (n = 22, mean age: 26.3 ± 1.9 years) were imaged once at corresponding time points (t₀: n = 11; t₁: n = 11). Segment-wise, the glycosaminoglycan (GAG) content of lumbar IVDs (n = 195) was determined using glycosaminoglycan chemical exchange saturation transfer (gagCEST). Linear mixed models were set up to assess the influence of cohort and other variables on GAG content.

RESULTS

During preseason, IVD GAG values of ERs were significantly higher than those of controls (ERs(t₀): 2.58 ± 0.27% (mean ± standard deviations); controls(t₀): 1.43 ± 0.36%; p ≤ 0.001), while during post-competition recovery, such differences were not present anymore (ERs(t₁): 2.11 ± 0.18%; controls(t₁): 1.89 ± 0.24%; p = 0.362).

CONCLUSIONS

Professional elite-level rowing is transiently associated with significantly higher gagCEST values, which indicate increased lumbar IVD-GAG content and strong remodeling effects in response to training. Beyond professional rowing, core-strengthening full-body exercise may help to enhance the resilience of the lumbar spine as a potential therapeutic target in treating back pain.

Mechanical loading influences the lumbar intervertebral disc. A cross-sectional study in 308 athletes and 71 controls

There is evidence in animal populations that loading and exercise can positively impact the intervertebral disc (IVD). However, there is a paucity of information in humans. We examined the lumbar IVDs in 308 young athletes across six sporting groups (baseball, swimming, basketball, kendo, soccer, and running; mean age 19 years) and 71 nonathletic controls. IVD status was quantified via the ratio of IVD to vertebral body height (IVD hypertrophy) and ratio of signal intensity in the nucleus to that in the annulus signal (IVD nucleus hydration) on sagittal T2-weighted magnetic resonance imaging. P values were adjusted via the false discovery rate method to mitigate false positives. In examining the whole collective, compared to referents, there was evidence of IVD hypertrophy in basketball (P ≤ .029), swimming (P ≤ .010), soccer (P = .036), and baseball (P = .011) with greater IVD nucleus hydration in soccer (P = .007). After matching participants based on back-pain status and body height, basketball players showed evidence of IVD hypertrophy (P ≤ .043) and soccer players greater IVD nucleus hydration (P = .001) than referents. Greater career duration and training volume correlated with less (ie, worse) IVD nucleus hydration, but explained less than 1% of the variance in this parameter. In this young collective, increasing age was associated with increased IVD height. The findings suggest that basketball and soccer may be associated with beneficial adaptations in the IVDs in young athletes. In line with evidence on other tissues, such as muscle and bone, the current study adds to evidence that specific loading types may beneficially modulate lumbar IVD properties.

Exercise for the intervertebral disc: a 6-month randomised controlled trial in chronic low back pain

BACKGROUND CONTEXT

Muscle, bone and tendon respond anabolically to mechanical forces. Whether the intervertebral disc (IVD) can benefit from exercise is unclear.

PURPOSE

To examine whether exercise can beneficially affect IVD characteristics.

STUDY DESIGN/SETTING

This is a single-blinded 6-month randomised controlled trial (ACTRN12615001270505) in an exercise and physiotherapy clinic.

PATIENT SAMPLE

Forty patients with chronic non-specific low back pain (NSCLBP) are included in this study.

OUTCOME MEASURES

The primary outcome was lumbar IVD T2 time (MRI). Secondary outcomes included IVD diffusion coefficient and IVD expansion with short-duration lying.

METHODS

Twenty patients progressively loaded their lumbar IVDs (exercise) via an exercise programme involving progressive upright aerobic and resistance exercises targeting the trunk and major muscle groups and were compared to twenty patients who performed motor control training and manual therapy (control). Testing occurred at baseline, 3 months and 6 months.

RESULTS

Seventeen exercise and fifteen control patients completed the interventions. There were no group-by-time differences in T2 time of the entire IVD (exercise 94.1 ± 10.0 ms vs. control 96.5 ± 9.3 ms, p = 0.549). Exercise patients had shorter T2 time in the posterior annulus at 6 months (82.7 ± 6.8 ms vs. 85.1 ± 8.0 ms, p = 0.028). Exercise patients showed higher L5/S1 apparent diffusion coefficients and decreased IVD height at 3 months (both p ≤ 0.050). After adjustments for multiple comparisons, differences lost statistical significance. Per-protocol and intent-to-treat analyses yielded similar findings.

CONCLUSIONS

This trial found that 6 months of exercise did not benefit the IVD of people with NSCLBP. Based on this index study, future studies could investigate the effect of exercise on IVD in different populations, with different types, durations and/or intensities of exercise, and using different IVD markers. These slides can be retrieved under Electronic Supplementary Material.