High intensity, short duration pulling in heavy horses: physiological effects of competition and rapid weight change

Abstract

BackgroundThe Heavy Horse Pull is a competition where teams of two horses pull an increasingly heavy sled for a short distance. Similar to human wrestlers, some horses may undergo rapid weight change in order to enter a lower weight category. The objectives were to study the physiological effects of this practice as well as of the pulling competition in draft horses.ResultsFifty horses were divided into light-, middle- and heavyweight categories based on their arrival weights and competed 1–3 days after. Body weight was measured upon arrival and pre-competition. Blood was sampled for chemistry and high sensitivity cardiac troponin T (hscTnT) at arrival, pre- and post-competition in 34, 26 and 20 horses, respectively. Body weight increased significantly between arrival and pre-competition for light (7.2% (Median: 62.8Kg (41.7–77.0)) and middle (8.6% (Median: 80.5Kg (62.7–90.9)) weight categories. Change in body weight was correlated (r = 0.69, p = 0.002) with competition ranking for middleweights. The ratios of weight pulled to team body weight were 2.7 (1.9–2.8), 2.6 (2.5–2.6) and 2.4 (2.2–2.5) for the lightweights, middleweights and heavyweights, respectively. Blood chemistry indicated hemoconcentration on arrival in the middleweight and lightweight horses. Hemoconcentration was not seen on arrival in some horses with marked rapid weight change. Overall, no chemistry parameter changed between pre- and post-competition. The hscTnT stayed within normal range post-competition.ConclusionsWhile horses arrived to the event with indications of hemoconcentration, they appeared to have sufficient time to rehydrate prior to competition, and the effects of the competition were reversible within 3 h.

Effects of different load on physiological, hematological, biochemical, cytokines indices of Zanskar ponies at high altitude

“…The level of total protein, albumin, globulin, creatinine and urea were found to be significantly increased. Greco-Otto et al, 2017 noticed that there was a strong correlation between plasma total protein, albumin, globulin, creatinine and urea. This increase in the values of these parameters was due to dehydration during intense work (Munoz et al, 2011).…”

“…The increase in ALT level after carrying more weight in these ponies addressed the question regarding the potential changes in ALT level post-exercise. It is reasonable to assume, that measurements of ALT levels might be reflected by load carrying programs in ponies at high altitude and impact on muscle mass because there is a strong correlation between AST and ALT, as well as between CK and ALT (Greco-Otto et al, 2017). Recently one of the study observed that low ALT blood activity, as a biomarker for increased weakness, is associated with lower baseline fitness of post-acute myocardial infarction and post-cardiac surgery patients going through a cardiac rehabilitation program.…”

Assessing the impact of draught load pulling on welfare in equids

“…Physiological indicators such as blood temperature ( 58 , 59 ), rectal temperature ( 39 , 42 , 46 , 60 , 61 ), heart rate ( 30 , 39 , 40 , 42 , 46 , 47 , 49 , 61 , 62 ), respiration rate ( 30 , 39 , 42 , 46 , 61 ), hematological profile ( 30 , 40 , 49 , 61 , 62 ), muscle fiber composition ( 39 , 40 , 63 ), creatinine kinase ( 62 , 64 , 65 ), lactate dehydrogenase ( 42 , 62 , 63 ), alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, citrate synthase, and 3-hydroxy acyl-CoA dehydrogenase ( 42 , 63 , 64 ), have been investigated in relation to the load pulling capabilities of equids ( Figure 5 ). However, the conditions under which this work has been done have been highly variable, so generalization of the results is difficult.…”

“…However, this change in rectal temperature does not recover even after 1 h of rest after the end of exercise ( 46 ). This may be due to the faster metabolic rate in donkeys than horses ( 64 ), but this has yet to be investigated in relation to load pulling. These studies indicate that work speed may be more important than draught force in influencing body temperature, but a direct comparison between work speed and draught force in load pulling equids is never made.…”

“…Since its rise in plasma activity is greater in untrained horses than in trained horses, measuring creatinine kinase concentrations could be a helpful fitness indicator ( 42 ). At a maximum load that a horse can pull over a distance of 14 feet, during heavy horse pull competition at Calgary Stampede ( 71 ), creatine kinase enzyme activity increases from 174 to 225.5 IU/L ( 64 ). However, in a team of two horses (one colt and one stallion), pulling draught load of 0.93 kN draught force while working together for 150 min, creatine kinase enzyme activity increases from 62.1 to 101 U/L and from 127 to 167 U/L in colt and stallion, respectively ( 62 ).…”