Physical Activity to Reduce Fatigue in Rheumatoid Arthritis: A Randomized Controlled Trial

Objective

Effective treatments for rheumatoid arthritis (RA) fatigue are limited. We tested the effect of a pedometer‐based intervention on increasing physical activity and decreasing fatigue among individuals with RA.

Methods

Participants completed baseline questionnaires; had 1 week of activity monitoring; were randomized to control (education [EDUC]), pedometer and step‐monitoring diary (PED), or pedometer and diary plus step targets (PED+) groups, and were followed for 21 weeks. At week 10, questionnaires were administered by phone to all participants. During the final week, all participants again had 1 week of activity monitoring. Primary outcomes were changes in average weekly steps and fatigue (Patient‐Reported Outcomes Measurement Information System 7‐item questionnaire) from baseline to week 21. Secondary outcomes were self‐reported disease activity, physical function, pain interference, and depressive symptoms. Changes in steps were tested using a linear mixed model. Changes in fatigue were tested with repeated‐measures models, including baseline, week‐10, and week‐21 scores.

Results

A total of 96 individuals participated. Eight did not complete the 21‐week assessments. Both intervention groups significantly increased steps (+1,441 [P = 0.004] for PED and +1,656 [P = 0.001] for PED+), and the EDUC group decreased steps (‐747 [P = 0.14]) (group‐by‐time interaction P = 0.0025). Between‐group changes in fatigue were not significantly different (interaction P = 0.21). Mean changes in fatigue scores from baseline to week 21 were ‐1.6 (with‐group P = 0.26), ‐3.2 (P = 0.02), and ‐4.8 (P = 0.0002) for EDUC, PED, and PED+ groups, respectively. Function and self‐reported disease activity also improved in the PED and PED+ groups.

Conclusion

Provision of pedometers, with and without providing step targets, was successful in increasing activity levels and decreasing fatigue in this sample of individuals with RA.     

Comparison of Fatigue Properties and Fatigue Crack Growth Rates of Various Implantable Metals

The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion resistance and biocompatibility. The highly biocompatible Ti-15Zr-4Nb-4Ta alloy exhibited an excellent balance between strength and ductility. Its notched tensile strength was much higher than that of a smooth specimen. The strength of 20% cold-worked commercially pure (C.P.) grade 4 Ti was close to that of Ti alloy. The tension-to-tension fatigue strength of an annealed Ti-15Zr-4Nb-4Ta rod at 10⁷ cycles was approximately 740 MPa. The fatigue strength of this alloy was much improved by aging treatment after solution treatment. The fatigue strengths of C.P. grade 4 Ti and stainless steel were markedly improved by 20% cold working. The fatigue strength of Co-Cr-Mo alloy was markedly increased by hot forging. The notch fatigue strengths of 20% cold-worked C.P. grade 4 Ti, and annealed and aged Ti-15Zr-4Nb-4Ta, and annealed Ti-6Al-4V alloys were less than those of the smooth specimens. The fatigue crack growth rate of Ti-15Zr-4Nb-4Ta was the same as that of Ti-6Al-4V. The fatigue crack growth rate in 0.9% NaCl was the same as that in air. Stainless steel and Co-Cr-Mo-Ni-Fe alloy had a larger stress-intensity factor range (ΔK) than Ti alloy.     

Fatigue in aviation

Pilot fatigue is a significant, but often under-reported problem in both civilian and military aviation operations. Although estimates vary, official statistics indicate that fatigue is involved in at least 4-8% of aviation mishaps, and surveys of pilots and aircrew members reveal that fatigue is an important concern throughout today's 24/7 flight operations. Regulatory efforts aimed at limiting flight hours and ensuring at least minimal periods of crew rest have to some extent mitigated fatigue-related difficulties in the cockpit, but it is clear that much remains to be done about this insidious threat to air safety. Scheduling factors, sleep deprivation, circadian disruptions, and extended duty periods continue to challenge the alertness and performance levels of both short-haul and long-haul pilots and crews. Solutions for these problems are not straightforward, but they can be developed through the cooperative efforts of scientists, regulators, managers, and the pilots themselves. Over the past 20 years, scientific understanding of human sleep, fatigue, and circadian rhythms has expanded considerably. The thorough integration of this new knowledge into modern crew-resource management practices will facilitate the establishment of optimal crew scheduling routines and the implementation of valid aviation fatigue countermeasures.