Though the author describes how Visual Sensory Deprivation exercises may be incorporated into hammer throw training he makes it clear that VSD may be beneficial for any discipline requiring balance, precision, power, strength and conditioning.
By Nils Oliveto, MSC, CSCS
Sports science research has significantly contributed over the years in improving Paralympic performances (7). Various studies have demonstrated that the physical preparation of visually impaired athletes competing in Paralympics events incorporates similar strength/power exercises as their sighted counterparts (9). However, intricate physiological distinctions do exist between visually-impaired Paralympians and Olympic athletes within a training framework. The components associated with the former include altered postural stability, non-visual proprioception and modified somatosensory systems (3). A greater understanding of these components can therefore potentially create an innovative training scheme for non-visually impaired competitors. The rationale of this paper is to propose a way to enhance proprioceptive specific-strength using a Visual Sensory Deprivation (VSD) method catered for elite sighted athletes. This article will use the hammer-throw in track & field to demonstrate the application of such a VSD protocol.
HAMMER THROW BASICS
The hammer throw is one of four throwing events in track & field in which a metal ball (7.26kg-16 lb for men/4kg-8.8lb for women), attached by a steel wire and a handle, is thrown as far as possible for distance. This action is executed by generating a rotational motion that creates an acceleration of the implement up to the point of release (5). The throwing motion can be divided into three phases as shown in Figure 1.
• Phase 1: the preliminary winds (one, two, or more swings of the implement above the head, the body in a static position, both feet remaining in contact with the ground).
• Phase 2: the turns (3 or 4 spins with the hammer in which the athlete rotates with the implement as a system, alternating the feet’s double and single supports in each turn, inside a 7-foot diameter circle (12).
• Phase 3: the final release for the toss.
The goal of the preliminary winds (Phase 1) is to slowly create a horizontal velocity build-up and to properly establish an initial plane of motion to the hammer. This opening sequence of the throw allows for a smooth transition into the subsequent rotational patterns occurring in Phase 2 (the turns) all the way through the final release (Phase 3) of the throwing motion (12,13).
Motor awareness of a hammer thrower includes the following: body position during the rotational throwing motion, level of muscular tension with the hammer (required to maintain balance between the centrifugal force pull of the implement and the centripetal force applied by the athlete) and the amplitude of movement (maximizing the length of the radius between the hammerhead and the thrower’s center of gravity, i.e. the hips) (4). It is interesting to point out that the sum of the dynamic-phases executed by hammer throwers yields the largest kinetic energy of any athletic events (15).
PROPRIOCEPTIVE AND SOMATOSENSORY ELEMENTS
Proprioception is the body’s own sense of position and motion, which includes body segment static position, accurate perception of forces, displacement, timing of movement velocity, acceleration, and applied muscular contractions during the performance of a particular motor activity (19,22). Ogard et al. (14) point out that balance is not synonymous with proprioception. Balance is defined as the capacity to uphold the center of mass within the base of support and relies on precise inputs from the somatosensory, vestibular and visual systems (11). In regards to specific proprioception in the hammer-throw, it is the processing of the Central Nervous System (CNS) which determines the relative position/motion of the whole body (14) while keeping balance with the hammer implement. The sequence from the sensory systems leading up to proprioception is demonstrated in Figure 2.
The somatosensory system provides multiple feedbacks to the CNS from numerous muscle (primary from the muscles spindles) and connective tissue receptors contributing to balance and proprioception (6). The vestibular system, which has a gyroscopic equilibrium mechanism located near the inner ear, contributes critically to both navigation and spatial orientation by using its receptors (comprised of semicircular canals and otolith organs) and making them highly perceptive to any variations in position of the head and subsequently of the entire body (1). Given the complex rotational nature of the hammer throw’s biomechanics, the vestibular system is fundamentally important in its function.
The visual system controls primarily the information delivered by the other sensory systems. The visual and proprioceptive systems provide the athlete’s CNS with essential inputs about what is occurring in his or her external and internal environments (11). These centers supervise the body’s position awareness in space, essential in an event which requires an immense level of balance such as the hammer-throw.
Insufficient balance control and proprioception are often associated with a diminution in muscular strength (8). Proprioception can therefore be heightened through specific resistance training, ensuing an amplified degree of physical awareness (18). This occurs as perceptions surface from the receptors of the CNS, which presents the body with data about internal and external environments (18). Specific resistance training develops an athlete’s aptitude to sense the muscles as they execute the various drills. Consequently, athletes performing training workouts with a VSD can enhance the proprioceptive, vestibular, and somatosensory systems (2,18).
BLOCKING VISUAL-SENSORY INPUTS
One method of enhancing proprioceptive effectiveness is to block inputs from the visual sensory system, i.e. the eyes, with a sleep mask. Meir reports that the brain centers, which control and regulate balance, are indirectly receiving about 20% of the optic nerve’s fibers (11). Because the athlete’s eyes deliver an estimated 80% of the inputs processed, they clearly play a vital part in the overall performance mechanism (11). The proprioceptive and the visual system are so complexly linked that when the visual system is deprived of any incoming information, one must adapt by relying more on the other components (i.e. somatosensory and vestibular) of the balance system (2,18). Such synergy between the tactile and gyrating mechanisms creates a compensation which boosts the information influx from both the somatosensory/vestibular systems and offsets the absence of incoming visual data (Figure 3).
Stronks et al. state that a visual input deficit can be offset by the improved skills development of a blinded individual’s other sensory systems (21). The visual cortices of a sightless person are recruited by other operating brain zones and become reactive to physical and auditory information, as revealed by neuroimaging research investigations (21). It can therefore be argued that an athlete’s enhanced motor awareness (or any other specific strength motion) could also increase over time when the movements are performed upon the return of a full visual sensory access if proprioceptive sensitivity is augmented.
Figure 3: Effect of blocking visual sensory inputs on proprioception
The hammer throwing motion is quite paradoxical. On one end of the spectrum, the athlete must keep the upper body completely relaxed. This is paramount for adequate rotational velocity in Phase 2 (12). Such a sequence will ultimately lead to an optimal whipping effect and peak velocity release in Phase 3. On the other end of the spectrum, strength output in the preliminary winds and the subsequent turns is quite significant. Full body strength and postural stability are therefore mandatory in keeping the athlete in balance while maintaining the axis of rotation throughout the throwing motion (12,23).
Figure 4: Blindfolded VSD hammer-winds
According to Aydog et al., the visual system is connected to the proprioceptive centers of the brain and directly impacts this dynamic postural stability (3). Figure 4 is showing a strength-specific dynamic postural stability VSD drill (blindfolded), mirroring the preliminary hammer winds (Phase 1) motion by using a chain, a handle and regular gym plates. The length of this makeshift ‘’hammer’’ is about the same as the regular competitive hammer (121 cm/4 ft) for a higher level of specificity associated with the elliptical trajectory of the ‘’real’’ hammer winds motion. This drill requires a higher effort in proprioceptive dynamic postural stability since visual data is not accessible to the visual system.
Table 1 suggest a VSD 4-week microcycle (linear model) proprioceptive specific-strength example using the hammer-winds drill. This suggested training sample is designed for an experienced male hammer thrower (+ 60m/+ 200ft) who competes with the regulation 16 lb implement.
For the purpose of avoiding asymmetrical muscular development and optimizing proprioception coming from different angles’ stimuli, it is suggested to perform this motion both clockwise (CW) and counter-clockwise (CCW). The first warm-up set is executed keeping the eyes open with a regular competition hammer (16lb for a male thrower). The number of repetitions (CW and CCW) are in parentheses. For the subsequent VSD (blindfolded) sets, regular gym plates can be used with weights, chosen accordingly, relative to the proprioceptive strength level of the thrower. The coach also has the option of requesting the athlete to vary the speed of execution for an even greater range of neuro-motor stimulus via the larger moment of inertia created by the hammerhead’s velocity. Such a core stability drill, requiring a higher level of proprioceptive specific strength, can be incorporated into a scaled back intensity classical strength/power training with a suggested recovery time of 3-4 minutes in between sets (12).
It is imperative to point out that any blindfolded dynamic activity has an increased risk of injury, so safety is crucial in avoiding accidents (18). Athletes might have to rely on their coach for security precautions, guidance and technical corrections. However, as they gain more abilities over time, they will learn to trust their sensory systems senses and accomplish the workout with greater precision (18). Coaches should only allow their athletes to proceed with heavier loads if the VSD’s technique is correctly and safely executed while blindfolded.
INCORPORATING VSD INTO A PERIODIZATION PROGRAM
The neural, muscular, and physiological stress resulting from all aspects of the athlete’s global physical preparation cannot be ignored when designing a peak performance plan (17). Oliveto emphasizes the importance of accurate quantification of the overall training volume load parameters within a strength-training periodization (16). It is also imperative to regularly modify all training components (power development, velocity work, agility, technical throwing sessions) throughout the athletic year (16).
Figure 5: Relationship between the overall training volume & intensity level with the frequency of VSD exercises incorporated into a monocycle yearly periodization plan
When used as a stability-strength exercise, such as the hammer winds drill, VSD is best used in the general preparatory phase of a periodization yearly program (12). Figure 5 shows a monocycle yearly periodization plan for a hammer thrower looking for peak performance in the summer (competitive) season. The graph presents the overall training volume (strength-power training, throwing sessions, speed-agility movements, etc.) and the overall intensity level in relationship with a suggested frequency level of the VSD exercises method.
The overall training volume and intensity vary throughout the year. Typically, a higher volume in the preparatory phases and an increased intensity in the pre-competitive/competitive phases are usually prescribed (16,17). The graph also indicates that the frequency of the VSD training method should be fairly important in the preparatory phases, while allowing itself to slowly decrease towards the peak performance season as VSD attributes should improve after each of the three previous macrocycles (Spring, Winter and Fall).
Figure 6 displays various VSD blindfolded strength-specific resistance exercises typically performed by hammer throwers throughout a yearly periodization plan. These movements are only some of the multitudes of ways an athlete can increase his/her proprioceptive strength-specific system by augmenting appropriate neuromuscular dexterities associated to subtle and intricate actions (13).
Figure 6: Various VSD blindfolded strength-specific exercises for the hammer throw.
NONVISUAL MOTOR TRAINING IN OTHER SPORTS
It is essential to realize that other sports can also benefit from nonvisual motor training in their respective resistance workout plans. If done safely and with the utmost level of proper coaching guidance (18), practical implications are virtually endless for all disciplines requiring balance, precision, power, strength and conditioning.
As discussed earlier, it is recommended to prescribe VSD strength-specific proprioceptive trainings to experienced competitors. Nevertheless, all athletic skill levels can benefit from the blindfolded approach when performing low intensity/event-specific techniques performed outside the weight room. Individuals with a blocked access to visual sensory data can still successfully develop muscular activity and movement coordination for postural control by using nonvisual motor learning (3).
Examples of blindfolded/low-intensity/nonvisual motor actions in other sports can include: standing long jumps in jumping events, block starts motions in sprints, or release drills in the throws. Practical perspectives of modified visual sensory training can go a long way with the creative mind of a dedicated and safety-conscious track coach (11).
Proprioceptive strength-specific strategies are seldom incorporated into an athlete’s training protocol (20). Several coaching methods, while beneficial, may comprise the same actions repeated over a span of many years (10), thus resulting in a possible performance stagnation. Visual Sensory Deprivation (VSD) exercises, although atypical, offer the option to program the athlete’s body while preventing the tedious aspect of standard strength or power workouts. The addition of a VSD protocol into a training methodology can increase the athlete’s ability to accomplish complex motions more thoroughly.
It is important to underline the possible dangers and risks of using a VSD approach if the athlete is not properly guided by a qualified track & field coach (18). Maximizing strength potential is essential in performance enhancement, but the coaching staff should avoid skipping the basics as it could have a negative impact on novice athletes. This training method is definitely more appropriate for competitors who have reached their near-strength potential as opposed to beginners.
Planning a wide variety of resistance exercises can help the athlete achieve a decrease in the likelihood of injuries and overtraining, while increasing the prospect of attaining optimal results (16). Using a methodical attempt to incorporate some form of VSD scheme into a strength and conditioning training system is currently not a widely used formula. A closer look into the visual sensory system and an in-depth comprehension of proprioception can assist track & field coaching professionals in expanding their training repertoire that could thrive and magnify their athletes’ performances (11,14).
- Angelaki DE and Cullen KE. Vestibular System: The Many Facets of a Multimodal Sense. Annual Review of Neuroscience 31: 125-150, 2008.
- Auxter D, Pyfer JC, and Huettig C. Principles and Methods of Adapted Physical Education and Recreation (9th ed.). Dubuque, IA: McGraw-Hill, 2001. pp. 557–580.
- Aydog E, Aydog ST, Çakci A, and Doral MN. Dynamic Postural Stability in Blind Athletes Using the Biodex Stability System. International Journal of Sports Medicine 27: 415-418, 2006.
- Dapena J. Some biomechanical aspects of hammer throwing. Athletics Coach, 23: 12-19, 1989.
- Elalem SFM. Evaluation of Hammer Throw Technique for Faculty of Physical Education Students Using DartFish Technology. Journal of Applied Sports Science 6: 80-87, 2016.
- Gandevia SC, Smith JL, Crawford M, Proske U, and Taylor JL. Motor commands contribute to human position sense. The Journal of Physiology 571: 703-710, 2006.
- Keogh JWL. Paralympic sport: an emerging area for research and consultancy in sports biomechanics. Sports Biomechanics 10: 234-253, 2011.
- Killebrew SS, Petrella JK, Jung AP, and Hensarling, RW. The Effect of Loss of Visual Input on Muscle Power in Resistance Trained and Untrained Young Men and Women. Journal of Strength and Conditioning Research 15: 495-500, 2013.
- Loturco I, Nakamura FY, Winckler C, Bragança JR, da Fonseca RA, Moraes-Filho J, Zaccani WA, Kobal R, Cal Abad CC, Kitamura K, Pereira LA, and Franchini E. Strength-power performance of visually impaired Paralympic and Olympic judo athletes from the Brazilian national team: a comparative study. Journal of Strength and Conditioning Research 31: 743-739, 2017.
- McGill S. Core training: Evidence translating to better performance and injury prevention. Strength and Conditioning Journal 32: 33–46, 2010.
- Meir R. Conditioning the Visual System: A Practical Perspective on Visual Conditioning in Rugby Football. Strength and Conditioning Journal. 27: 86-92, 2005.
- Murofushi K, Babbitt, D, and Ohta, K. Supplemental Exercises for Core Stability Which Utilize the Concept of Parametric Oscillation in the Hammer Throw. Strength and Conditioning Journal. 39: 71-81, 2017.
- Murofushi K, Sakurai K, Umegaki K, and Takamatsu J. Hammer acceleration due to thrower and hammer movement patterns. Sports Biomechanics 6: 301–314, 2007.
- Ogard WK. Proprioception in Sports Medicine and Athletic Conditioning. Strength and Conditioning Journal. 33: 111-118, 2011.
- Ohta K, Umegaki K, Murofushi K, Komine A, and Sakurai S. Training aid system for hammer throw based on accelerometry. XXII Congress of the International Society of Biomechanics, Cape Town, South Africa, July 5–9, 2009.
- Oliveto N. Establishing Volume Load Parameters: A Different Look in Designing a Strength Training Periodization for Throwing Events. Strength and Conditioning Journal. 26: 52-55, 2004.
- Oliveto N. Historical Foundations of Peak Performance Periodization and Its Applications to Elite Hammer Throwing [master’s thesis]. Norman, OK: University of Oklahoma, 2000.
- Piletic, CK and Piper T. Including Individuals with Visual Impairments in the Weight Room. Strength and Conditioning Journal. 27: 14-20, 2005
- Reiman BL and Lephart SM. The sensorimotor system, part I: The physiologic basis of functional joint stability. Journal Athletic Training 37: 71-79, 2002.
- Siff MC. Supertraining 5th ed. Denver, Co: Supertraining Institute, 2000. pp.172.
- Stronks HC, Nau AC, Ibbotson MR, and Barne N. The role of visual deprivation and experience on the performance of sensory substitution devices. Brain Research 1624: 140-152, 2015.
- Struzik A, Pietraszewsk B, Kawczyński A, Winiarski S, Juras G, and Rokita A. Manifestations of Proprioception During Vertical Jumps to Specific Heights. Journal of Strength Conditioning Research 31: 1694-1701, 2017.
- Waller MA, Gersick MJ, Townsend RJ, and Ford CN. Strength and conditioning preparation for the transitional track and field thrower. Strength and Conditioning Journal. 36: 71-78, 2014.
Nils Oliveto is an Olympic analyst for CBC Radio-Canada television, a peak performance consultant/speaker and a physical education instructor at Lionel-Groulx College in St-Thérèse (Québec, Canada). He has color-commentated the summer and winter Olympic Games, including various World Championships and World Cups events, in both track & field and sliding winter sports (bobsled, luge, skeleton). He holds a Master of Science degree from the University of Oklahoma in Exercise Science with a research emphasis on periodization and training methodology. A former National Collegiate Athletic Association (NCAA) scholarship hammer-thrower in Oklahoma, he has also represented Canada in various international athletic meets. He earned his Certified Strength and Conditioning Specialist (CSCS) through the National Strength and Conditioning Association (NSCA) and was previously published in the Strength and Conditioning Journal. He will broadcast this year’s 2021 Olympic and Paralympic Summer Games in Tokyo, Japan for CBC Radio-Canada Sports French channel.