The phenomenon of a sticking point is multifactorial and underlain by complex interactions between different contributing factors that are both athlete-specific and exercise-specific. This makes the problem of addressing an athlete’s sticking point a major challenge in practice. A systematic approach is necessary—guided by empirical observations made in rigorous and controlled conditions reported in well-designed studies, a detailed analysis of an athlete’s performance should be used to identify the most promising training strategy. We identified five key strategies that a resistance training practitioner (coach or athlete) should understand and consider:

1. Target muscle strengthening using isolation work, 2. ROM-specific training using partial repetitions, 3. Development of momentum preceding the sticking point, 4. Exercise technique alteration, and 5. Accommodating or variable resistance use.

These are reviewed next—we explain the key ideas that motivate their use, outline how and when they should be applied, and highlight the target populations that they are most likely to benefit.

Isolation Work

Many studies on the sticking point examined the stage in a lift at which the sticking point was observed for different exercises [6, 9, 13, 54, 55]. These findings can offer valuable insight into different strategies that can be employed to improve performance. In particular, by considering the biomechanical context (lever arms, elongation, etc.) in which different muscles contribute to the lift in the vicinity of the sticking point as well as the corpus of collected electromyography (EMG) data, in many cases it is possible to identify the muscle (or more broadly a functional muscle group) that can be considered the ‘weakest link’ [8, 20]. A straightforward application of this observation involves the strengthening of these muscles and especially so at the elongation at which failure occurs. Indeed power- and weightlifters have a long tradition of so-called assistance work, which accomplishes precisely this [8, 56, 57]. Common examples include the inclusion of chest isolation exercises by athletes who exhibit the sticking point at the onset of the concentric phase in the bench press [58] or the use of various isolation exercises for elbow extensors by athletes who encounter difficulties in the terminal stages of the lift [59].

Partial Repetitions and Isometric Training

At the point in the ROM of a lift at which failure occurs, it can be readily seen that increasing the effective force that a trainee can exert against the load at this point will improve performance (note that this does not imply that the sticking point is the only or even the optimal such point, as discussed at length by Arandjelović [20]). Owing to the principle of specificity of strength adaptations [19, 60]—that is, the observation that the inducted adaptational stimulus to resistance exercise is the greatest for lifting conditions similar to those experienced during exercise—the most direct manner of addressing a sticking point is by employing partial repetitions [18] or isometric training [61, 62]. In particular, numerous studies have demonstrated that partial repetitions, whereby the load is lifted only through a limited part of the ROM in an exercise, is effective at increasing strength at approximately ±10°–20° from the trained joint angle [63, 64]. Similarly, functional isometrics that involve the application of force by the trainee against a load against a practically immovable obstacle (e.g. the pushing of a barbell against pins in a power rack) [65] have been shown to be successful at increasing strength at the specifically trained ROM [61, 62, 66, 67].

Considering the general consensus of empirical findings that suggest that partial and isometric training has limited potential for providing a sustained stimulus for muscular hypertrophy [62], these training modalities are of most direct interest to performance-oriented athletes. For athletes seeking increases in muscle mass the potential benefit may be indirect in that overcoming a specific sticking point may facilitate the use of greater loads in conventional training (which involves a combination of eccentric, concentric, and isometric contractions). However this potential value has to be carefully considered in the context of the invested time and effort, the associated neural fatigue, and psychological factors [68].

Momentum

In Sect. 2 we noted that the sticking point in a lift may not necessarily occur at the point of greatest biomechanical disadvantage. For example, even if at a certain point in the ROM there is a net force deficit (i.e. the effective force an athlete is able to exert against the load is lower than the experienced external resistance), if the load has significant momentum the deficit may not effect a difficulty in overcoming this part of the motion. This observation leads to a popular training strategy employed by strength and power athletes that focusses on increasing force and its rate of development in the phases of a lift that precede a sticking point [69–71]. In particular so-called speed work involves the use of repeated low-intensity (\(\approx 50\)–60 % of one repetition maximum) sets, typically with short rest periods (45–60 s), with repetitions performed in a maximally accelerated fashion. This modality has been widely used by powerlifters [51, 69, 72, 73] in training for all three of the competition lifts (bench press, squat, and deadlift), and recent models described in the academic literature have started to elucidate the mechanisms underlying its effectiveness [20].

A different use of momentum for overcoming a sticking point involves the application of external momentum. In contrast to speed work training whereby the load is supplied momentum via the action of the muscles inherently involved in a particular exercise, external momentum is developed through the use of muscles otherwise not involved in a lift [14]. Though widely used by both recreational trainees and elite athletes [74, 75], this practice is often, if not usually, dismissed (as suggested by the morally loaded colloquial term ‘cheating’ used to describe it [76–79]) on the grounds that the use of excessive resistance increases the risk of injury and reduces the load experienced by the target muscles [76]. However recent models suggest that when used in moderation, external momentum can be safely used to apply greater force on target muscles as well as increase their time under tension (TUT) [14]. Considering safety and practical constraints (e.g. external momentum is easier to impart on isolation exercises, which generally involve the use of lighter loads), external momentum is of most use to athletes seeking increases in muscle size such as bodybuilders.

Technique Alteration

The motion against resistance can be thought of as being effected by the sum of forces of muscles dynamically contributing to the lift, nonlinearly modulated by the given mechanical context [16]. Even when a single functional muscle group and its effects on motion around a single hinge joint are considered, the isolated characteristics of the effective force are greatly different from those of the muscle in isolation [20]. For complex multi-joint lifts, which involve a greater number of functional groups of muscles, the characteristics are far more multifaceted. This observation provides a powerful means of modifying a lift in a manner that eliminates or reduces the impact of a sticking point—by changing the style of exercise execution the biomechanical context can be changed. Distally speaking, this means that the points in the ROM at which a particular muscle are particularly strong (or weak) can be altered [4, 54], the time under tension (and with it fatigue) preceding the sticking point can be affected [8, 20] as well as the speed of contraction of contributing muscles at different points in the lift [19, 72]. In proximal terms the aim is to “flatten out” the difficulty of the lift [80]. Specific examples of how this may be achieved include alterations to the grip [54] or the stance [81, 82] width of the lifter, changes in the orientations of joint flexion/extension (or adduction/abduction) planes [3, 4, 82], adjustments in the synchronisation of movements across different joints [7], as well as numerous others [83].

It is important to stress that safety should always be an important consideration when attempting a modification of lifting technique. An unfamiliar biomechanical context itself can lead to injury so any changes should be done in a gradual fashion and using conservative loads until the lifter is familiarised with the newly adopted technique. In addition certain lifting styles may inherently carry certain risks, e.g. a wide grip on the bench press may increase the risk of shoulder injury and pectoralis major rupture [84], rounding of the back in the deadlift (which minimises the moment arm of the load around the hip) the risk of spinal injuries [85], and buckling of the knees (valgus collapse—poorly synchronised or excessive tibial internal rotation and adduction relative to the knee flexion angle in a given stance) in the squat the risk of knee injuries [86].

Exercise technique alterations are of most obvious utility to strength athletes whose primary aim is to complete a lift with the greatest amount of load, providing that the alterations are within the range permitted by their sport (e.g. see The International Powerlifting Federation [87] and The International Weightlifting Federation [88]). However employed in a targeted manner they can benefit a wide range of trainees. Bodybuilders for example may use them to place a greater emphasis on a certain muscle group (thereby possibly increasing the resistance experienced by the target muscles while reducing the total load lifted) while athletes may benefit from a style that is more suitable to their individual strengths and weaknesses and more effective at mimicking the manner in which they would perform a certain mechanical action.

Accommodating and Variable Resistance

The term accommodating resistance refers to purposeful modifications of the effective load experienced in an exercise throughout a repetition [19, 89–92]. This technique is most often used in training by powerlifters [69] but also by other types of athletes in general strength and conditioning work [89, 91, 93]. One popular method of introducing accommodating resistance involves the fixing of an elastic band between the load (such as a barbell) and floor (or other fixed object, e.g. the power cage or the frame of a resistance machine). Typically, as the weight is lifted, the band is stretched and the resistance felt by the trainee increased [94–96]. Another commonly used alternative involves the use of heavy chains [97, 98], which are uncoiled and lifted off the floor during the lift thereby effecting an increase in resistance.

Both types of accommodating resistance are commonly recommended in powerlifting training for “overloading the top of the range of motion” [99–101] or increasing the rate of force development [93, 102, 103]. As such, when it comes to performance-oriented athletes (such as powerlifters), they are of most use in cases when the sticking point occurs in the terminal stages of a lift. For bodybuilders, or indeed other athletes looking to increase their muscle size, for whom the immediate aim is not the increase in performance in a particular exercise per se, the opposite prescription seems reasonable, i.e. an overload of the part of the ROM that is overcome easily. In this manner the entire ROM of an exercise can be made approximately uniformly challenging and closer to maximal resistance experienced throughout a set [80].

The mechanics of training aids such as elastic bands and chains limit the functional form of resistance alterations that can be achieved [104] (for a detailed review see Arandjelović [19]). Nevertheless other means of applying variable resistance are readily available in many training facilities [48, 104]. The most common ones include machines that achieve more complex loading patterns through the use of cams [80, 105], counterweights [106–108], and viscous resistance [104, 109]. The resistance modification achieved by each of these is quite different in nature: cams offer resistance variability as a function of the position in a lift, counterweights as a function of the acceleration of the load (i.e. the second derivative of position), and viscous resistance as a function of the speed of the load (i.e. the first derivative of position) [109]. By choosing an appropriate modification, which may include a combination of two or more of the aforementioned modalities, sophisticated effects can be achieved that best suit a particular athlete’s goals [109–111].

By varying the length of the moment arm of the force transmitted by the machine, cams allow a fixed force (the weight of the load) to produce a changing effective force experienced by the athlete. The force envelope is determined by the design, i.e. the shape of the cam [111]. One of the key ideas motivating the use of cams is that of attempting to match the resistive force of the machine with the force-length characteristics of human skeletal muscles [80, 104, 112, 113]. This would make them more suitable for hypertrophy-oriented athletes such as bodybuilders. The alteration of resistance characteristics through the use of counterweights is rather different in nature and may be described as reactive in the sense that the resistance is not dependent on the part of the exercise ROM per se but rather the instantaneous ease or difficulty of lifting exhibited by the trainee. As the detailed analysis presented by Arandjelović [109] demonstrated, at times when the load is moving with ease, i.e. with an increased acceleration of the load, the acceleration deficit between the load and the counterweights acts in a manner that increases resistance. The converse is true as well: when the acceleration of the load reduces, the effect of the counterweight is increased and the resistance felt by the trainee lessened, the least resistance being felt when acceleration reaches zero or becomes negative (as is the case in the exercise ROM preceding the sticking point) [109]. This is of most use to hypertrophy-oriented athletes for whom high tension sustained over time is crucial [114, 115].