The complete citation for the Costill study comparing training twice a day at 10,000m or more to once a day at 5,000m or less and finding no advantage is:
Costill, D.L., R. Thomas, R.A. Robergs, D.D. Pascoe, C.P. Lambert, S.I. Barr, and W.J. Fink. 1991. Adaptations to swimming training: Influence of training volume. Medicine and Science in Sports and Exercise 23: 371-377.
It's unclear whether these volume levels have much relevance to most masters swimmers...
The complete citation for the Costill study comparing training twice a day at 10,000m or more to once a day at 5,000m or less and finding no advantage is:
Costill, D.L., R. Thomas, R.A. Robergs, D.D. Pascoe, C.P. Lambert, S.I. Barr, and W.J. Fink. 1991. Adaptations to swimming training: Influence of training volume. Medicine and Science in Sports and Exercise 23: 371-377.
It's unclear whether these volume levels have much relevance to most masters swimmers...
