List of papers
Some incremental progress, just taking the obvious first action of "search google scholar for 'benefits of exercise on productivity'", followed by a search for "benefits of strength training on productivity" after remembering that the first one wasn't quite right (but maybe still useful enough to include)
Including random quotes that seemed most relevant (did not search anything very hard)
Does strength training programme improve work task performance in young adults with Down Syndrome?
The effect of the PRT programme on work task performance will be assessed using two tests (a) repetitive weighted box stacking and (b) weight carry test (pail carry). The repetitive weighted box stacking test requires the participants to repetitively lift 10 kg boxes, from the floor to a table 75 cm off the ground. The number of boxes stacked in one minute is measured. The weighted pail carry requires participants to carry two 20 litre buckets each weighing 10 kg around an oblong 10 m course marked with cones. The total distance covered in 30 seconds is measured in metres. Running is not permitted for safety reasons. These measures are recommended by the American College of Sports Medicine  and have demonstrated changes in people with intellectual disability [34, 35].
The impact of a self-paced exercise program on productivity and health outcomes of 32 adult workers in a large federal office complex was investigated during 3 months.
Walking was the sole form of exercise. The first month, during which no walking occurred, was the control period. The second and third months were the experimental period. Participants were divided into three levels based on initial weight and self-determined walking distance goals. Productivity (using the Endicott Work Productivity Scale), walking distance (using a pedometer), and health outcomes (blood pressure, weight, pulse rate, and body fat percentage) were measured weekly. Results from this study, based on a paired t test analysis, suggest that although the self-paced exercise program had no impact on productivity, it lowered blood pressure and promoted weight loss. Further study using a larger sample and a controlled experimental design is recommended to provide conclusive evidence.
Exercise is more than medicine: The working age population's well-being and productivity
In Denmark 15 randomized controlled trials have been conducted, introducing exercise at the workplace enrolling >3500 workers. The interventions lasted from 10 to 52 weeks and offered ~1 h weekly supervised exercise during working hoursaccording to the concept of intelligent physical exercise training (IPET) that is based on evidenced sports sciences training principles and tailored to work exposure, employee health status, and physical capacity. Questionnaire surveys and health checks including blood and muscle sampling were performed at baseline and follow-up. The job groups included: office and computer workers, dentists, industrial technicians, cleaning personnel, health care workers, construction workers, and fighter/helicopter pilots.
Poor health among employees implies substantial costs for the companies. The costs relate to increased sickness presenteeism (decreased on-the-job-performance while being at the workplace) as well as absenteeism (habitual absence from work) leading to loss of work productivity.37 Sickness presenteeism was assessed as self-reported on-the-job-performance, using questions in regard to productivity, work ability, and quantity and quality of work.
Importantly, in spite of spending 1 h a week performing physical exercise training during work time, in none of our studies we found a decrease in the variables underlying on-the-job-performance.
However, we did, in an intention-to-treat analysis, find a significant 8% increase in productivity of the intervention among health care workers after 3 months but not after 1 year of intervention.38 Likewise among dentists we found improved self-reported quality of work.18
Interestingly, some exploratory analysis of our RCTs actually revealed some relevant findings: productivity increased with decreased neck/shoulder pain, and with improved muscle strength—in particular trunkflexion and extension—as well as decreased BMI among health care workers.37Further, workers with sedentary monotonous tasks (office/computer) —who were physically active at leisure compared with those being inactive—perceived less stress and more energy. These perceived differences were underlined by corresponding differences in physiological measures of the stress-hormonecortisol.39 Regarding sickness absenteeism analysis on our RCTs so far has not identified significant changes with the interventions.
The Benefits of Exercise for the Clinically Depressed
While most studies have employed walking or jogging programs of varying lengths, the efficacy of nonaerobic exercise has also been assessed. For example, in comparison with a control condition, resistance-training programs reduced symptoms of depression (resistance training vs. control resulted in BDI reduction of 11.5 vs. 4.6, respectively, p < .01, and HAM-D reduction of 7.0 vs. 2.5, respectively, p < .01).21
Aerobic and nonaerobic modes of exercise have also been compared to determine if certain types of activities are more effective than others. Doyne and colleagues22 compared the efficacy of running with that of weight lifting. Forty depressed women served as participants and were randomly assigned to running, weight lifting, or a wait-list control group. Participants were asked to complete 4 training sessions each week for the 8 weeks of the program. Depression was assessed at mid- and post-treatment and at 1, 7, and 12 months follow-up. Results indicated that the 2 activities were not significantly different, and that both types of exercise were sufficient to reduce symptoms of depression (running vs. weights vs. control resulted in BDI reduction of 11.1 vs. 13.6 vs. 0.8, respectively, p < .01, and HAM-D reduction of 6.7 vs. 8.7 vs. a 1.0 increase, respectively, p < .01).
Further, there were no differences between the 2 treatment groups during follow-up with respect to the percentage of participants who remained nondepressed. Similarly, a study by Martinsen et al.23 assessed 90 depressed in-patients who were randomly assigned to aerobic or non-aerobic exercise. Aerobic exercise consisted of jogging or brisk walking, and nonaerobic exercise included strength training, relaxation, coordination, and flexibility training. The program was 8 weeks in length, and participants exercised for 60 minutes, 3 times per week. Those in the aerobic group exhibited an increase in PWC compared with those in the nonaerobic group. However, both groups experienced a significant reduction in depression score (p < .001), but there were no significant differences between the groups with respect to the magnitude of change in depression score (p > .10).