Is running good or bad for your knees? A systematic review and meta-analysis of cartilage morphology and composition changes in the tibiofemoral and patellofemoral joints.

BACKGROUND: The general health benefits of running are well-established, yet concern exists regarding the development and progression of osteoarthritis. AIM: To systematically review the immediate (within 20 min) and delayed (20 min-48 h) effect of running on hip and knee cartilage, as assessed using magnetic resonance imaging (MRI). METHOD: Studies using MRI to measure change in hip or knee cartilage within 48 h pre- and post-running were identified. Risk of bias was assessed using a modified Newcastle-Ottawa Scale. Percentage change in cartilage outcomes were estimated using random-effects meta-analysis. Certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation tool. RESULTS: Twenty-four studies were included, evaluating 446 knees only. One third of studies were low risk of bias. Knee cartilage thickness and volume decreased immediately after running, with declines ranging from 3.3% (95% confidence interval [CI]: 2.6%, 4.1%) for weight-bearing femoral cartilage volume to 4.9% (95% CI: 4.43.6%, 6.2%) for patellar cartilage volume. T1ρ and T2 relaxation times were also reduced immediately after running, with the largest decline being 13.1% (95% CI: -14.4%, -11.7%) in femoral trochlear cartilage. Tibiofemoral cartilage T2 relaxation times recovered to baseline levels within 91 min. Existing cartilage defects were unchanged within 48 h post-run. CONCLUSIONS: There is very low certainty evidence that running immediately decreases the thickness, volume, and relaxation times of patellofemoral and tibiofemoral cartilage. Hip cartilage changes are unknown, but knee changes are small and appear transient suggesting that a single bout of running is not detrimental to knee cartilage.

Trials of an acoustic transponding fish tag compass.

The instantaneous orientation of a fish can be determined by attaching a magnetic compass sensor to it and then by acoustically telemetering the information to a research vessel's electronic sector scanning sonar. The sensor is housed in a cylindrical capsule with an acoustic transponder to which it is electronically interconnected. Its size and weight are such that it can be fitted to fish of about 40 cm length and above. An operational life of 52 h is obtained from the tag when it is interrogated by the sonar at a consistent rate of 2 pulses s-1. If the rate is reduced by half, the life can be extended to about 68-70 h. Directional accuracy is limited to +/- 22.5 degrees by the physical size of components used in the sensor. Trials of the prototype are described.

Fish heart rate telemetry in the open sea using sector scanning sonar.

Real time monitoring of heart rate from free-swimming fish in the open sea has been used in conjunction with high resolution sonar to track plaice and observed the variation in heart rate in relation to environmental parameters. The heart rate can be observed at the same time as the acoustic picture of the sea bed or the midwater volume of sea surrounding the fish.