Surgeon, educator and sculptor, McKenzie was born in Lanark County, Ontario. After graduating in medicine at McGill University, he became its Medical Director of Physical Training in 1894. A pioneer in physical education, he served as a surgeon with the R.A.M.C. in World War I, and developed rehabilitation techniques that were soon widely adopted. He won international claim for his sculptures of athletes, while his bronze medallion, the Joy of Effort, was mounted at the Olympic Stadium at Stockholm in 1912. His most significant sculpture is the Scottish-American War Memorial in Edinburgh.