A horse that comes out of the stable a little stiff or does not move completely smoothly during training may be affected by various issues. If your horse is clearly and persistently irregular in its movement, you should call a veterinarian for a lameness examination. If the issue is mainly “needing to warm up” or occasional stiffness, it is worth investigating the possible cause. Depending on the origin, there are different ways to support your horse.

Muscle-related stiffness

Stiffness can originate in the muscles. This is more likely in horses that have only recently started training, such as young horses, or in horses that work intensively. During training, muscles are put under strain with the aim of making them stronger and more resilient. Training causes small micro-damages in the muscle fibers, which are repaired by the body during the recovery period after training. As a result, the muscles become stronger than before. This is a natural process and part of training, and in principle it is not harmful. However, it is important to follow a correct training schedule in which heavier work is alternated with active recovery (free movement, walking, or groundwork). Keep in mind that “workload” for a young horse that has just been backed may consist of only 15 minutes of walk and trot, while for an experienced sport horse it means something entirely different. Recovery also differs between horses. The same training principles apply to all: a training stimulus causes micro-damage, which is repaired by the body during a rest period of one or two days, after which a new stimulus is needed to repeat the process. Only by building up training in this way will your horse become stronger and fitter. Seek proper advice or read more about this to create a suitable training schedule for your horse. A little stiffness after a demanding training session is not a problem, as long as the muscles are given enough time to recover.

Muscle acidosis: training and differences between breeds

During training, the body may enter an anaerobic (low-oxygen) state. This causes the muscles to become acidic, and lactate (lactic acid) is temporarily stored in the muscle tissue, for example during more demanding dressage exercises. When the horse is allowed to walk again after the exercise, the body removes the lactate from the muscle cells. The point at which this acidosis occurs depends on your horse’s fitness and training level. For a young horse, a single canter round may already lead to muscle acidosis. For a well-trained event horse, it may only occur after six or seven minutes of cross-country work. As a rider or trainer, you can often feel that your horse is becoming acidic when it starts to feel “stronger in the hand” or shows resistance. When the muscles become acidic, it becomes harder for the horse to maintain balance, which you feel while riding. This is not disobedience. If you notice this, walk for a few minutes on a long rein and allow your horse to catch its breath. There is no point in continuing when your horse is acidic. It is painful and will lead to increased stiffness in the days following training. Your horse may also develop a negative association with training if you keep going when its body is already “in the red zone.” If something is not working in your training—an exercise or a jump—always ask yourself whether your horse might be suffering from muscle acidosis, especially if you are riding a Friesian or a draft-type horse. Scientific research has shown that Friesians have a different type of muscle fibers compared to breeds such as KWPN horses or Thoroughbreds. As a result, they become acidic more quickly, particularly in canter and especially if they are not yet well accustomed to it. Research conducted on young Friesian stallions during the Central Performance Test showed that less frequent and shorter canter training led to better progress and improved training tolerance. Many people believe that draft horses also differ from riding horses in this respect. Always observe your own horse carefully and adapt the training to the individual. At the same time, it is important to train with sufficient intensity—doing too little will not make your horse stronger or improve its endurance. Also take conditions such as PSSM2 into account, as these can cause your horse to become acidic more quickly.

Joint-related stiffness

Stiffness can therefore result from micro-damage or acidosis in the muscles, but it can also originate in the joints. Joints are the places in the body where bones meet and move against each other. Cartilage at the ends of the bones and synovial fluid within the joint help absorb impact and allow smooth movement. Minerals are important for the development and maintenance of bones, cartilage, and synovial fluid. In particular, silicon and magnesium should be present in sufficient amounts in the diet. Phosphorus and calcium are also essential, but most horses receive ample amounts through a normal ration. As a horse ages, cartilage may wear down and the production of synovial fluid may decrease. This can cause aches and stiffness, especially at the beginning of movement. Movement stimulates the production of synovial fluid, which is why older horses often mainly need a calm and gradual warm-up. If you walk for ten minutes or more before gradually introducing short trot intervals, stiffness in many older horses will disappear on its own. It also helps if your older horse has plenty of free movement and can move around throughout the day instead of standing still in a stall.

Osteoarthritis

Over the course of life, minor damage and wear can occur in the skeleton. Joints become less smooth and small inflammations may develop. Many older horses have a mild form of osteoarthritis, which makes it harder for them to get going. Pain can be alleviated with plant-based anti-inflammatory and analgesic substances, such as clove extract. As with other forms of stiffness, plenty of free movement and calm warm-ups are the best remedies. Give your horse time and keep it moving as much as possible. When a horse loses muscle mass—also a natural part of aging—the load on the joints increases. That is why it is important to continue training the muscles. They hold your horse together and absorb movement, reducing the strain on the joints. Think of the muscles as a kind of protective armor around the vulnerable bones: the better the armor, the less stress and wear on the skeleton.

Waste products in the joints

In addition to muscle acidosis, intensive training can also lead to the accumulation of waste products in the joints, specifically uric acid. This is produced as a by-product of intense work. While the horse is actively moving, the body cannot immediately transport this waste product to the kidneys, so uric acid is temporarily stored in the joints in the form of uric acid crystals. These crystals have sharp edges and can cause pain and joint stiffness after intense training. Over time, they are naturally eliminated. This process can be supported with herbal extracts, such as a combination of turmeric, boswellia, horsetail, blackcurrant, and bamboo.

Supple horse?

Whether your horse occasionally shows stiffness originating from the muscles, the joints, or both: in all cases, it is essential that your horse has sufficient muscle mass. Well-developed muscles form a functional support around the joints and absorb a large part of the impact. To keep your horse’s muscles supple and healthy, a well-designed training schedule with adequate stimuli and sufficient active recovery is crucial. Muscle development can be supported with magnesium and vitamin E. For healthy joints, free movement and the mineral silicon are especially important. If your horse experiences stiffness due to osteoarthritis or the accumulation of waste products in the joints, plant-based supplements may provide support.