Abstract
uscular strength has a strong positive impact on cardiometabolic health and tness. However, building up strength endurance requires e ortful exercises. From a health perspective, it is important to understand which psychological strategies help people deal with straining exercise. Self-regulation strategies like if-then planning (also known as implementation intentions) appear particularly promising because they might directly alter how people deal with exercise-induced sensations. However, research on the e ects of if-then planning on exercise performance has yielded mixed results so far. One possible reason for these inconsistent results is the lack of tailored interventions and the neglect of potential moderators. To address this, we investigated the e cacy of if-then plans that were tailored to perceived limits of endurance performance (i.e., perceptions of exertion versus pain). In addition, we investigated the e ects of these tailored if-then plans while taking into account the potentially moderating e ects of individual di erences in implicit theories. Speci cally, we were interested in the role of implicit theories about athletic performance (i.e., entity versus incremental beliefs) and about the limitation of athletic performance by mental versus physical factors (i.e., mind-over-body beliefs).N=66 male students (age:M=25.8 years,SD=3.2 ) performed a static muscular endurance task twice (measurement: baseline task vs. main task) and were randomly assigned to a goal or an implementation intention condition. They were instructed to hold two intertwined rings for as long as possible while avoiding contacts between them (measure of performance: time-to-failure and errors). After the baseline task, participants were
male students (age:M=25.8 years,SD=3.2 ) performed a static muscular endurance task twice (measurement: baseline task vs. main task) and were randomly assigned to a goal or an implementation intention condition. They were instructed to hold two intertwined rings for as long as possible while avoiding contacts between them (measure of performance: time-to-failure and errors). After the baseline task, participants were either given an implementation intention or were simply asked to rehearse the task instructions. The content of the instruction depended on whether they ascribed ultimate baseline task termination to perceptions of exertion or pain. After the main task, implicit theories on athletic ability were assessed. No di erences in performance emerged between conditions. In the implementation intention condition, however, stronger entity beliefs were associated with increasing time-to-failure when participants planned to ignore exertion but with decreasing time-to-failure when they planned to ignore pain. This pattern of results was reversed with regard to mind-over-body beliefs. These ndings indicate that the e cacy of psychological strategies hinges on recreational athletes' beliefs regarding athletic performance. Keywords: muscular endurance performance; self-regulation; implementation intentions; psychobiological model; Borg scales; implicit theories; limits of athletic performance Int. J. Environ. Res. Public Health2020,17, 2576; doi:10.3390 /ijerph17072576 /journal/ijerph
Int. J. Environ. Res. Public Health2020,17, 2576 2 of 21 1. Introduction Research shows that physical tness contributes strongly to the current and future health of adults and children alike [1,2]. Even though most work has focused on the importance of cardiorespiratory tness for health outcomes, muscular tness is increasingly recognized as a relevant factor as well [3]: it is linked to lower cancer mortality risk in men [4], lower overall mortality [5], as well as enhanced bone health, boosted self-esteem, and reduced adiposity in children [3,6]. Although these bene ts are widely known and despite recommendations by major health organizations to engage in muscular endurance training [7] to enhance cardiometabolic health and tness [8], a large number of people is still not active: an estimated 77% of U.S. citizens do not ful ll physical activity recommendations on cardiovascular and strength training [9]. To complicate matters further, building up muscular strength requires to endure muscular exercises for a su cient time at an optimal intensity, which might be perceived as too e ortful and encourage premature termination of an ongoing exercise. From a health perspective, it is therefore paramount to understand which factors in uence and eventually limit muscular endurance performance and whether there are strategies to e ectively deal with these factors. A large body of research investigated physiological limits to exercise tolerance [1013] and suggests that people might not fully deplete their physiological resources in straining exercise [14,15]. This points toward an important role of psychological factors in exercise termination. For example, according to the psychobiological model of exercise tolerance [16,17], perceived exertion critically limits endurance performance. The model states that endurance exercises are terminated when applying additional e ort seems either unjusti ed or impossible [16,17]. Applied to muscular endurance performance, this suggests increasing self-regulatory demands [18]: as upholding certain levels of performance becomes more and more di cult (i.e., the perception of exertion rises), self-regulatory challenges rise as well (e.g., enduring increasing sensations of pain). One strategy that might help to deal with these challenges is the self-regulatory strategy of if-then planning (also referred to as
to muscular endurance performance, this suggests increasing self-regulatory demands [18]: as upholding certain levels of performance becomes more and more di cult (i.e., the perception of exertion rises), self-regulatory challenges rise as well (e.g., enduring increasing sensations of pain). One strategy that might help to deal with these challenges is the self-regulatory strategy of if-then planning (also referred to as forming implementation intentions [19,20]), which has already been investigated in the context of health (i.e., [2123]) and various other domains [24]. In an if-then plan, a person speci es how to achieve a goal (e.g., enduring an e ortful task). It comprises selecting a goal-relevant situation (e.g., upcoming sensations of muscle pain) and linking it to a goal-directed behavior (e.g., ignoring the pain and continuing the exercise) in an if-then format: If I encounter Situation S, then I will perform Behavior B! (e.g., And if my pain becomes too great, then I tell myself: I can still keep going!). Making if-then plans is assumed to activate the mental representation of the situation which thereby becomes easier to remember and to recognize [25,26]. Research further indicates that if-then planning automates the initiation of the goal-directed behavior [19,20]. Accordingly, implementation intentions are seen as an e cient bottom-up form of action control compared to goal intentions, which merely specify what to do but not how to do it (e.g., I want to ignore the pain and continue the exercise!) [27] and are thus less conducive to automatic behavior initiation. This is an essential aspect especially in complex health behaviors like exercising that confront people with various barriers to perform successfully and to keep exercising. In support of this notion, one study showed that implementation intentions help athletes to recognize opportunities for hydration and to increase the intake of carbohydrate-electrolyte solutions during a cycling exercise by over 50% [28]. In a study with tennis players, implementation intentions on how to deal with intrusive thoughts, emotions and physiological states led to improved performance during matches [29]. More relevant for our present purposes, however, are investigations of the e ects of if-then planning in muscular
and to increase the intake of carbohydrate-electrolyte solutions during a cycling exercise by over 50% [28]. In a study with tennis players, implementation intentions on how to deal with intrusive thoughts, emotions and physiological states led to improved performance during matches [29]. More relevant for our present purposes, however, are investigations of the e ects of if-then planning in muscular endurance tasks. This research is scarce, though, and has so far produced inconsistent results. On the one hand, if-then plans helped participants deal with perceptions of pain in a ball-holding task: Planning to direct attention away from muscle pain and to initiate self-a rmative speech (And if my muscles hurt, then I will ignore the pain and tell myself: I can do it!) led to an increase in time-to-failure compared to a condition with a corresponding goal intention [30]. On the other hand, two similar studies focusing on time-to-failure in a rod-holding task found no e ects of if-then planning on performance. In one study [31], planning to ignore perceived
Int. J. Environ. Res. Public Health2020,17, 2576 3 of 21 exertion did not alter performance and actually increased exertion. Such a null- nding also emerged in the second study [18] in which participants planned to ignore perceptions of pain (as in the ball-holding study)although functional near-infrared spectroscopy (fNIRS) during task performance showed lower lateral prefrontal cortex activity among participants in the implementation intention condition, indicating lower activation in an area that is critical for e ortful self-regulatory control. Taken together, these results indicate that if-then planning a ects the correlates of muscular endurance performance but not necessarily performance itself. Furthermore, it suggests that neither targeting perceptions of exertion nor targeting perceptions of pain yields consistent e ects of implementation intentions. This poses the question of what might cause the inconsistent ndings. It seems worthwhile to investigate whether the e ects of if-then planning are moderated by factors that were not yet accounted for. Here, we focus on two of these factors: First, it might matter whether people experience perceptions of exertion or perceptions of pain as limits to their own performance. Exertion refers to the conscious sensation of how hard, heavy, and strenuous a physical task is [32] and therefore re ects mental processes (e.g., the urge to quit). Pain, on the other hand, is de ned as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. [33] and thus re ects bodily processes (e.g., locomotor muscle fatigue or accumulation of lactic acid). Previous research provided the same plan to all participants (i.e., dealing with pain or dealing with exertion) and therefore does not provide information on whether and how individual di erences in experiencing mental versus bodily limits obscure implementation intention e ects. Second, it might matter to which degree participants believe that performance is generally limited versus improvable, and whether potential limits pertain to the mind versus the body. Such beliefs are commonly referred to as implicit theories that people may hold regarding attributes like intelligence [34]. These beliefs are commonly divided into two categories that describe how people judge the malleability of an
might matter to which degree participants believe that performance is generally limited versus improvable, and whether potential limits pertain to the mind versus the body. Such beliefs are commonly referred to as implicit theories that people may hold regarding attributes like intelligence [34]. These beliefs are commonly divided into two categories that describe how people judge the malleability of an attribute [3537]: People are said to hold entity beliefs if they think that an attribute is xed and stable, while they are said to hold incremental beliefs if they think that an attribute is exible and changeable. These beliefs in uence decisions, for example regarding what goals to pursue [36], but are usually unconscious [38]. People holding entity beliefs seek positive appraisals of their expertise and thus favor performance-oriented goals, while people holding incremental believes try to enhance their ability through acquirement and thus favor learning-oriented goals [35]. Learning-oriented goals are often (but not necessarily) associated with more bene cial outcomes than performance-oriented goals because they are conducive to using negative feedback as a means for further development rather than interpreting it as a mere sign of lack of ability. Considering research on implicit theories about willpower, it is implied that failing self-regulation after a short execution of self-control does not originate in people's actual self-control resources but is de ned by their beliefs on how much self-control they are able to exert [39]. This research underlines the important role which implicit theories have on behavior, as they for example disclose failures in self-control [40]. This theorizing can be transferred to the exercise context, in which implicit theories pertain to the malleability of athletic abilities and thus in uence exercise behavior [41,42]. Speci cally, people holding incremental beliefs see athletic ability as changeable by learning, e ort, and training, whereas people holding entity beliefs see it as innate and stable, and thus unchangeable by training and e ort [42,43]. Interestingly, a person can hold both incremental and entity beliefs at the same time, thinking of athletic ability as an inherited capability that can still be enhanced through commitment and e
ability as changeable by learning, e ort, and training, whereas people holding entity beliefs see it as innate and stable, and thus unchangeable by training and e ort [42,43]. Interestingly, a person can hold both incremental and entity beliefs at the same time, thinking of athletic ability as an inherited capability that can still be enhanced through commitment and e ort [43]. Incremental beliefs about athletic ability are connected to higher self-driven motivation, enjoyment and grit as they are accompanied by expectations of improved performance [42,44]. Entity beliefs, on the other hand, are more likely to lead to frustration and discouragement because they render failure as feedback on a lack of ability [42,44]. It is therefore plausible that entity and incremental beliefs moderate implementation intention e ects in various ways. For instance, entity theorists could undermine their e ects due to doubts that planning improves a performance that one deems unchangeable. Alternatively, people holding entity beliefs might be more likely to respond well to an external strategy (i.e., if-then plans) as means to avoid
Int. J. Environ. Res. Public Health2020,17, 2576 4 of 21 failure in the upcoming performance (and thus avoid feedback on a lack of ability [45]). People with incremental theories might, in contrast, be amenable to if-then plans because they consider changes in performance as generally possible and might be more receptive to learning for improvement [46]. They may, however, perform better regardless of external self-regulatory strategies, as they are shown to be more persistent in challenging exercise tasks compared to entity theorists [47]. Given these considerations, it is plausible that implicit theories a ect implementation intention e cacy. To our knowledge, this interaction has not been addressed so far. Moreover, the interaction between beliefs and implementation intentions could be even more intricate when we consider that participants might perceive exertion or pain as limit to their performance. As we have argued above, exertion and pain serve as signals that mental or bodily limits have been reached, respectively. To understand the (lack of) implementation intention e ects, it might therefore be important to know whether people believe that performance is ultimately limited by mental (mind) rather than by physical factors (body)which we refer to as mind-over-body beliefs. For instance, people who perceive the body as limiting factor in athletic performance (i.e., low mind-over-body beliefs) might interpret pain as a signal that this limit is reached and deem further attempts to improve futile. This might undermine the e ectiveness of planning to simply ignore pain as a means to endure longer. This could be di erent for people who believe that performance is ultimately limited by mental factors (i.e., high mind-over-body beliefs). To them, pain does not signal that a performance limit is reached, rendering plans targeting the regulation of pain more auspicious. Analogous arguments can be constructed with respect to exertion: people holding low (versus high) mind-over-body beliefs might not (versus might) identify perceptions of exertion as a limiting signal, which might increase (versus decrease) the e cacy of planning to ignore exertion. In sum, the e ectiveness of plans targeting the regulation of exertion versus pain might depend on people's
auspicious. Analogous arguments can be constructed with respect to exertion: people holding low (versus high) mind-over-body beliefs might not (versus might) identify perceptions of exertion as a limiting signal, which might increase (versus decrease) the e cacy of planning to ignore exertion. In sum, the e ectiveness of plans targeting the regulation of exertion versus pain might depend on people's beliefs about athletic ability (entity, incremental, mind-over-body), their perception of limiting sensations during an endurance task (pain, exertion), and the interaction of beliefs and limits. Taken together, the aim of this study was twofold. First, we wanted to improve upon previous research designs. In previous studies, all participants received the same if-then plan that targeted either perceived exertion [31] or pain [18,30]. These studies did not take into account whether these sensations were in fact limiting the performance of individual participants. To address this shortcoming, we asked participants to state whether they had terminated the baseline task because of exertion or pain and then gave them an if-then plan that was tailored to their individual reason for task termination. Second, we wanted to investigate whether the e cacy of if-then planning is in uenced by participants' implicit theories about athletic ability. While there are studies on the in uence of entity and incremental beliefs on the motivation in physical activity and enjoyment of sports (e.g., [42,44,48]), we are not aware of studies on the importance of implicit theories for the e ectiveness of self-regulation strategies. As we have outlined above, there are several ways in which the beliefs resulting from implicit theories might interact with plan e ects and with sensations of exertion or pain. For instance, entity and incremental beliefs could be di erentially conducive to planning e ects. Moreover, beliefs about physical versus mental limits of performance could a ect implementation intention e ects depending on whether people struggle with sensations of pain or exertion. Beyond these two major aims, studies on if-then planning e ects on endurance performance were so far a icted by a high inter-individual variability especially with regard to time-to-failure (which is common in
Moreover, beliefs about physical versus mental limits of performance could a ect implementation intention e ects depending on whether people struggle with sensations of pain or exertion. Beyond these two major aims, studies on if-then planning e ects on endurance performance were so far a icted by a high inter-individual variability especially with regard to time-to-failure (which is common in endurance performance research, see [49,50]). This variability might have obscured potential di erences between goal and implementation intention conditions. We therefore added a baseline measure that allowed us to account for preexisting di erences in endurance performance. These changesincreased statistical power with a baseline measure and if-then plans tailored to perceived limits of endurance performance (i.e., perceptions of exertion versus pain) in combination with potentially moderating e ects of participants' individual beliefs about athletic ability (entity, incremental, mind-over-body)should further advance our understanding of when and how if-then planning a ects endurance performance.
Int. J. Environ. Res. Public Health2020,17, 2576 5 of 21 2. Materials and Methods 2.1. Participants and Design We recruited an all-male sample ofN=66 participants (age:M=25.8 years,SD=3.2) to minimize gender-related variance in endurance performance [31,50]. This sample size allows us to detect medium-to-large di erences (d=0.70; a typical e ect size of implementation intentions isd=0.65, see [19]) between the goal and the implementation intention condition in two-sided t-tests ( =0.05). The study adopted a 2-within (measurement: baseline task vs. main task) 2-between (condition: goal intention vs. implementation intention) design; participants were randomly and equally assigned to conditions. As third factor, we measured whether participants identi ed perceived exertion or pain as limiting their performance in the baseline task (limit: exertion versus pain). More participants named exertion (48 in total, including 23 in the implementation intention condition) than pain (18 in total; including 10 in the implementation intention condition) as their limit, with a similar distribution across conditions, 2(1,N=66)=0.782,p=0.782. Six participants ( ve in the implementation intention condition) were excluded from data analysis due to deviations from study protocol (the exclusion of those six participants did not change the pattern of results in terms of signi cance). The remaining participants reported exercisingM=6.7 hours per week (SD=4.7), of which 33.3% were related to strength training. Fifty-seven participants stated to be engaged in a variety of sport activities, having performed their main sport activity for an average ofM=7.8 years (SD=6.2), while 3 participants reported to be physically inactive (2 in the goal condition). Participants in the goal and the implementation intention condition did not di er in regard to their weekly training hours,p=0.448, or the duration of performing the main sport,p=0.306. When we advertised the study online, we emphasized that no current or recently healed injuries in shoulders, arms, or the back should be present to be eligible for participation. Moreover, we asked to avoid alcohol and strenuous exercise the day before the experiment and to refrain from consuming ca eine in the two hours before. Most participants complied with these requests with no di erences between conditions, p>0.545. Speci cally, 16 participants
Description
The study examines how implicit theories affect the efficacy of if-then planning in endurance tasks.