Anthony R.H. Oldham

Interactive processes link the multiple symptoms of fatigue in sport competition

Muscle physiologists often describe fatigue simply as a decline of muscle force and infer this causes an athlete to slow down. In contrast, exercise scientists describe fatigue during sport competition more holistically as an exercise-induced impairment of performance. The aim of this review is to reconcile the different views by evaluating the many performance symptoms/measures and mechanisms of fatigue. We describe how fatigue is assessed with muscle, exercise or competition performance measures. Muscle performance (single muscle test measures) declines due to peripheral fatigue (reduced muscle cell force) and/or central fatigue (reduced motor drive from the CNS). Peak muscle force seldom falls by <30% during sport but is often exacerbated during electrical stimulation and laboratory exercise tasks. Exercise performance (whole-body exercise test measures) reveals impaired physical/technical abilities and subjective fatigue sensations. Exercise intensity is initially sustained by recruitment of new motor units and help from synergistic muscles before it declines. Technique/motor skill execution deviates as exercise proceeds to maintain outcomes before they deteriorate, e.g. reduced accuracy or velocity. The sensation of fatigue incorporates an elevated rating of perceived exertion (RPE) during submaximal tasks, due to a combination of peripheral and higher CNS inputs. Competition performance (sport symptoms) is affected more by decision-making and psychological aspects, since there are opponents and a greater importance on the result. Laboratory based decision making is generally faster or unimpaired. Motivation, self-efficacy and anxiety can change during exercise to modify RPE and, hence, alter physical performance. Symptoms of fatigue during racing, team-game or racquet sports are largely anecdotal, but sometimes assessed with time-motion analysis. Fatigue during brief all-out racing is described biomechanically as a decline of peak velocity, along with altered kinematic components. Longer sport events involve pacing strategies, central and peripheral fatigue contributions and elevated RPE. During match play, the work rate can decline late in a match (or tournament) and/or transiently after intense exercise bursts. Repeated sprint ability, agility and leg strength become slightly impaired. Technique outcomes, such as velocity and accuracy for throwing, passing, hitting and kicking, can deteriorate. Physical and subjective changes are both less severe in real rather than simulated sport activities. Little objective evidence exists to support exercise-induced mental lapses during sport.A model depicting mind-body interactions during sport competition shows that the RPE centre-motor cortex-working muscle sequence drives overall performance levels and, hence, fatigue symptoms. The sporting outputs from this sequence can be modulated by interactions with muscle afferent and circulatory feedback, psychological and decision-making inputs. Importantly, compensatory processes exist at many levels to protect against performance decrements. Small changes of putative fatigue factors can also be protective.We show that individual fatigue factors including diminished carbohydrate availability, elevated serotonin, hypoxia, acidosis, hyperkalaemia, hyperthermia, dehydration and reactive oxygen species, each contribute to several fatigue symptoms. Thus, multiple symptoms of fatigue can occur simultaneously and the underlying mechanisms overlap and interact. Based on this understanding, we reinforce the proposal that fatigue is best described globally as an exercise-induced decline of performance as this is inclusive of all viewpoints.

Changing ecological constraints of practice alters coordination of dynamic interceptive actions

Abstract The ecological constraints of practice have a significant effect on the acquisition of functional information–movement couplings and learners need to converge on information-specifying perceptual variables. Consequently, the prolonged and widespread use of ball projection machines for the practice of interceptive actions may lack theoretical foundation because they afford information-specifying variables that are not present in competition. The timing and coordination of the forward defensive stroke in cricket batting were examined in experienced batters under two typical practice task constraints: batting against a representative “real” bowler and a representative bowling machine (mean delivery velocity 26.76 m·s−1 under both conditions). Significant adaptation of coordination and timing was observed under the different practice task constraints. For example, initiation of the backswing was later against a bowler and downswing was faster with a different ratio of backswing–downswing when batting against the bowling machine (47%–53%) compared with the bowler (54%–46%). Peak bat height differed under the two constraints (bowling machine: mean 1.56 m, s=19.89; bowler: 1.72 m, s=10.36 m). Mean length of front foot stride was shorter against the bowling machine (0.55 m, s=0.07 m) than the bowler (0.59 m, s=0.06 m). The correlation between initiation of backswing and front foot movement was much higher against the bowler (r = 0.88) than the bowling machine (r=0.65).

Nonlinear Pedagogy Underpins Intrinsic Motivation in Sports Coaching

A key challenge for sports coaches is to provide performers with learning environments that result in sustain- able motivation. In this paper, we will demonstrate that programmes based around the principles of Nonlinear Pedagogy can support the three basic psychological needs that underpin self-determined motivation. Coaches can therefore ensure that practice sessions provide for intrinsic motivation with its associated motivational and emotional benefits.

Changes in pulmonary transfer factor with menstrual cycle phase.

To determine whether lung transfer factor for carbon monoxide (T(L(CO))) alters during menstrual phase and if steroid hormone levels relate to these changes, T(L(CO)) and T(L(CO)) adjusted for both alveolar volume (T(L)/V(A)) and haemoglobin concentration, were measured at five predefined and hormonally confirmed menstrual phases in 13 women. No difference between phases was observed in T(L(CO)) or adjusted values. Moreover, there was no association between the maximal change in oestradiol, progesterone, or oestradiol:progesterone ratio and the change in T(L(CO)) measured at the same time. When the first five chronological measurements, regardless of the menstrual phase at which they were measured, were analysed, T(L(CO)) changed significantly (p<0.05) with a maximal change between the first and fourth test (-2.69+/-2.53, 95% confidence interval). Although these results indicate that the first in a series of T(L(CO)) measurements may be higher, we found neither menstrual cycle phase nor ovarian hormone-related changes in T(L(CO)), and conclude that its adjustment for menstrual phase may not be necessary.

Athlete and coach agreement: Identifying successful performance:

Traditional coaching views the coach as an informed resource and the athlete as a reflection of expert knowledge. Recent approaches have criticised a strictly coach driven model of expertise, and in doing so have acknowledged the unique and developing knowledge of athletes, which emerges from extended practice. The growth of the athlete’s contribution in the coach–athlete dyad invites interesting questions about the usefulness of athlete knowledge and the changing role of the coach. Athlete–coach agreement was assessed via a triangulation of quantitative boat speed data from a single sculler and matched to phases of successful rowing that rowers and coaches both agreed on. Coach and rower were able to identify when the boat was travelling its fastest or slowest. However, when the performance was marginally faster or slower, they disagreed, and generally the rowers were more accurate about the performance than their coach. Implications for contemporary coaching practices are considered.