Nearly 200 studies have examined the impact that either acute or long-term exercise has upon cognition. Subsets of these studies have been reviewed using the traditional narrative method, and the common conclusion has been that the results are mixed. Therefore, a more comprehensive review is needed that includes all available studies and that provides a more objective and reproducible review process. Thus, a meta-analytic review was conducted that included all relevant studies with sufficient information for the calculation of effect size (N = 134). The overall effect size was 0.25, suggesting that exercise has a small positive effect on cognition. Examination of the moderator variables indicated that characteristics related to the exercise paradigm, the participants, the cognitive tests, and the quality of the study influence effect size. However, the most important finding was that as experimental rigor decreased, effect size increased. Therefore, more studies need to be conducted that emphasize experimental rigor.

A causal chain linking exercise intensity, affective responses (e.g., pleasure–displeasure), and adherence has long been suspected as a contributor to the public health problem of physical inactivity. However, progress in the investigation of this model has been limited, mainly due to inconsistent findings on the first link between exercise intensity and affective responses. The purpose was to reexamine the intensity–affect relationship using a new methodological platform. Thirty young adults (14 women and 16 men) participated in 15-min treadmill exercise sessions below, at, and above their ventilatory threshold. The innovative elements were the following: (a) Affect was assessed in terms of the dimensions of the circumplex model; (b) assessments were made repeatedly during and after exercise; (c) patterns of interindividual variability were examined; (d) intensity was determined in relation to the ventilatory threshold; and (e) hypotheses derived from the dual-mode model were tested. Intensity did not influence the positive changes from pre- to post-exercise, but it did influence the responses during exercise, with the intensity that exceeded the ventilatory threshold eliciting significant and relatively homogeneous decreases in pleasure. Exceeding the intensity of the ventilatory threshold appears to reduce pleasure, an effect that could negatively impact adherence.

A model for systematic changes in patterns of inter-individual variation in affective responses to physical activity of varying intensities is presented, as a conceptual alternative to the search for a global dose – response curve. It is theorized that trends towards universality will emerge in response to activities that are either generally adaptive, such as moderate walking, or generally maladaptive, such as strenuous running that requires anaerobic metabolism and precludes the maintenance of a physiological steady state. At the former intensity the dominant response will be pleasure, whereas at the latter intensity the dominant response will be displeasure. In contrast, affective responses will be highly variable, involving pleasure or displeasure, when the intensity of physical activity approximates the transition from aerobic to anaerobic metabolism, since activity performed at this intensity entails a trade-off between benefits and risks. Preliminary evidence in support of this model is presented, based on a reanalysis of data from a series of studies.

To provide a quantitative synthesis of randomized controlled trials examining the effect of exercise training on symptomatic fatigue in persons with multiple sclerosis (MS). Electronic databases (Web of Science, PubMed, PsycInfo, and Google Scholar) were searched for articles published between 1960 and October 2012 by using the key words "fatigue," OR "tiredness," OR "energy," OR "mood," OR "lassitude," AND "exercise," OR "physical activity," OR "rehabilitation," OR "fitness" WITH "multiple sclerosis." The initial search resulted in 311 articles, of which 74 were reviewed in detail and 17 met the inclusion criteria and provided enough data to compute effect sizes (ESs; Cohen d). The meta-analysis was conducted using a meta-analysis software program, and a random-effects model was used to calculate the overall ES, expressed as Hedge g. The weighted mean ES from 17 randomized controlled trials with 568 participants with MS was 0.45 (standard error = 0.12, 95% confidence interval = 0.22-0.68, z = 3.88, p ≤ .001). The weighted mean ES was slightly heterogeneous (Q = 29.9, df = 16, p = .019). The cumulative evidence supports that exercise training is associated with a significant small reduction in fatigue among persons with MS.