Domestically Martinsen won Norwegian titles in the 15 km (1966, 1970), 30 km (1969, 1971) and 4 × 10 km relay (1970, 1972–1975, 1978).
Domestically Martinsen secured Norwegian championships in the 15 km (1966, 1970), 30 km (1969, 1971) and 4 × 10 km relay (1970, 1972–1975, 1978).