Wearable Weights: How much is too much? What gives the best gains?

By Athena Kepler DVM (Venture Compete Heal)

Increase performance times, elevate fitness, push the limits— we are all looking for ways to do these things for ourselves and for our K9 partners. Wearable weight equipment is a growing tool in the fitness bag. Wearable weights include vests and leg weights. These tools can increase resistance and demand on muscles in order to push your dog’s body and performance. However, with increased resistance and demand on the body also brings increased injury risk. We want to push our performance, but we do not want injuries. Injuries are the worst setbacks to reaching our goals because they often put us further back than we originally started. Wearable weights at too heavy of a weight can change how our body moves and drastically increase our risk while limiting the potential gains. Although there is limited research in dogs, there is good research in human fitness that aligns with the results of the limited k9 fitness research.

So, how much is too much? What weight and exercises produce the most gains? What is safe? — That is exactly what we will be discussing in this article.

Vest

Vests Weighted vests can increase performance by increasing the body’s workload. They can also change how the body moves and thus add abnormal stresses to joints, ligaments, tendons & muscles. However, there are some safe limits and techniques that can decrease the chances of injury with weighted vest.

Jumping Performance

It has been found that as little as 3-6% BM (meaning 3-6% of the body weight) is adequate to increase jumping workload. Jump performance is very responsive to weighted vest training.

The level of the athlete’s fitness directly affects the amount of increased performance. Untrained athletes had decreased power output during the work and had small increases in performance, while trained athletes had a 6% increased power output during the work and greater than 10% increase in jump performance after [1, 2]. Changes in jump performance can happen in as little as 3 weeks for trained athletes, however, unconditioned athletes need 7+ weeks with incremental weight increases (2% per 2 weeks) to see significant improvement [1, 2].

Lower weights (7-11%BM in humans) increased the speed and power output in 15s of continuous jumping [1, 2]. Low-weighted vests seem to be ideal for K9 athletes that have frequent jumping in their sport or activity (ie. agility, disc dog, etc.). Heavy-weighted vests (20-30%BM in humans) found a significant increase in power of jumps and higher maximum jump height [1, 2]. This type of resistance seems to be ideal for single high-intensity jumping sports/activities with adequate rest in between (ie. French ring, Schutzhund, dock diving, police/military K9, SAR, etc.).

Speed and Acceleration

Weighted vests increase speed performance but does not increase acceleration performance. Untrained athletes show more improvement with no weight and very low weights (%BM was not specified), however, most studies are in trained athletes [1, 2].

The duration of how long athletes can sprint at top speed increased by 5% (ex. 3 seconds faster for every minute) using low-weight (7-8%BM) in a 3-week program [2]. This seems ideal for prolonged sprint sports/activities (ie. lure-coursing, fast-cat, etc.).

For increasing maximum speed, 6-7 weeks at moderate weight (10-20%BM) for 20-30-meter sprints is adequate to make faster muscle contractions (faster strides) and greater muscle thrust (longer strides) [2]. This is ideal for quick speed sports/activities (ie. bitesports, lure-coursing, fast-cat, police/military k9, etc.) A combination of low-weight sprints (7-8%BM) and heavy-weight (10-20%BM) can increase sprint duration and maximum speed for any sport or activity with proper training program.

Endurance

Walking with 10-20%BM has been shown to have greater increase in endurance by 6-17% [1, 2]. Running with weighted vests does not improve endurance as well as walking (only a 0.5% increase for running). Training programs of 8-12 weeks show most significant changes in endurance.

Leg Weights

Leg-weights can aid in performance enhancement, balance and coordination. However, in comparison to vests, safe weight limits are significantly smaller and risk for injury is higher. Jumping seems to have lower benefits than weighted-vests, although sprinting and endurance performance can benefit.

Speed and Acceleration

Speed is minimally-to not change by use of leg weights. However, 3%BM leg-weights (humans) in trained athletes increased acceleration without changing the body’s normal sprinting movement [1-3].

Endurance

Leg weights double the energy needed to work. At increments of 1.4%BM increases workload almost 6 times [1-3]. Meaning it is 6 times harder to work with leg weights with 1.4%BM added weight. For dogs, 2%BM did not significantly change how the legs moved [4-7]. This weight (2%BM) at least doubles the
activity in major muscle groups (only select muscles will have 2+ times activation)[4-7].

It is found that leg weights increase the heart and breathing effort during walking and running [1]. However, walking with leg weights has greater benefits and higher heart and breathing effort than running.

Safety

Changing of joint angles adds stress to the tendons and ligaments around the joints. Loads over 20-40% overload knee musculature. 18%BM changes the joint angles during movement. Dogs have not been researched at weights above 15%BM. 12-15%BM has been shown not to change the dog’s movement
abnormally and is thus safe limit to use [4-7].

Muscle fatigue leads to injury so cut your training and reps in half of the normal unweighted reps and times. Any training with weight above 8%BM should be combined with decreased duration of workouts,
decreased frequency per week and reps, and decreased distance per rep [2]. Loads of 15%+BM cause the athlete to become fatigued 2x faster than without weight [2]. This means what the athlete could normally do for 2 minutes can now only be done for 1 minute before exhaustion. Same goes for increasing weight
levels over time- when moving up 2%BM reduce the work by half. Weight increments for trained athletes have been shown safe if done every week [8]. Untrained athletes should not have incremental weight increases less than every 2 weeks.

Dog safe limits for sprint work should not exceed 15%BM (due to limited research). Continuous Running at heavy weights increases the risk of injury. Controlled 20-30-meter sprints is more adequate to improve performance.
Walking with loads up to 20%BM is significant to increase endurance compared to running [2]. Continuous running with greater than 6%BM increases injury risk and does not produce adequate increases in endurance capabilities – Walk don’t run with heavy weight! Incremental weight increases of 2%BM per week in trained athletes and not less than 2 weeks for untrained athletes [2].

Conclusion

Understanding what performance increases, what fitness goals, what limits you want to push is the first step to a proper program using wearable weights. The next step is understanding the safe limits. And the third step is developing a proper program that incorporates your goals, correct incremental weight
schedule, duration and frequency modification schedule, and the correct number of weeks needed to reach the goals safely.

Let’s push the limits with our dogs. Let’s elevate performance and be better than we were yesterday. But most of all let’s do it safely and without injury or setbacks!

Highlights

• Endurance increased by walking with vest(10-20%BM) or leg weights (1-2%BM) rather than running.
• Greater than 8%BM vest or any leg weight must reduce duration and frequency of work
• Leg weight safe limits 2%BM
• 2%BM increments
• Untrained athletes need 7-8 weeks of very gradual program
• Vest safe to 15%BM in dogs at sprints of 20-30 meters
• 3-6%BM overloads the body
• 7-8%BM increases top speed sprinting duration
• 18.5%BM 25-meter sprints increase maximum speed
• 7-11%BM increases repetitive jumping
• 12-30%BM increases maximum jump height

References

1. James E. Graves, A.D.M., Physiological response walking with hand and snkel weights. Medicine and Science in Sports and Exercise, 1988. 20(3).
2. Macadam, P., J.B. Cronin, and K.D. Simperingham, The Effects of Wearable Resistance Training on Metabolic, Kinematic and Kinetic Variables During Walking, Running, Sprint Running and Jumping: A Systematic Review. Sports Med, 2017. 47(5): p. 887-906.
3.  Feser, E.H., P. Macadam, and J.B. Cronin, The effects of lower limb wearable resistance on sprint running performance: A systematic review. Eur J Sport Sci, 2019: p. 1-13.
4.  Carrier, D.R., S.M. Deban, and T. Fischbein, Locomotor function of the pectoral girdle 'muscular sling' in trotting dogs. J Exp Biol, 2006. 209(Pt 11): p. 2224-37.
5. Carrier, D.R., S.M. Deban, and T. Fischbein, Locomotor function of forelimb protractor and retractor muscles of dogs: evidence of strut-like behavior at the shoulder. J Exp Biol, 2008. 211(Pt 1): p. 150-62. 
6. Fife, M.M., et al., Function of the oblique hypaxial muscles in trotting dogs. J Exp Biol, 2001. 204(Pt 13): p. 2371-81. 7
7. Schilling, N., et al., Function of the extrinsic hindlimb muscles in trotting dogs. J Exp Biol, 2009. 212(Pt 7): p. 1036-52.
8. Macadam, P., et al., Acute kinematic and kinetic adaptations to wearable resistance during vertical jumping. Eur J Sport Sci, 2017. 17(5): p. 555-562.