A couple of your assumptions are flawed:
- Greater height and mass are not necessarily selected for in cold climates. Hauling mass around is expensive.
- Playing rugby and basketball does not in any way select for reproduction, so neither "increases" height.
So, with those dealt with, I present:
They're not Dutch or Finnish, but the ones in Greenland are Danish. Culturally, hunting prowess used to be prized, so that ticks the 'strength is admired or idolized' box.
Here's where the presumption of height and mass falls down, however: the average Inuit height is 5'4". They trend to higher BMI than the global average, because fat retention is important. Height is not. (Also, smaller people are stronger, pound for pound, than larger people.)
They're an excellent (20 000 years!) study in cold-climate adaptation, which includes both phenotypical and metabolic changes.
From the above-linked article:
These genetic mutations in the Inuit have more widespread effects. They lower "bad" LDL cholesterol and fasting insulin levels, presumably protecting against cardiovascular disease and diabetes. They also have a significant effect on height, because growth is in part regulated by a person's fatty acid profile. The researchers found that the mutations causing shorter height in the Inuit are also associated with shorter height in Europeans.
...
The mutations seem to be at least 20,000 years old, and may have helped many groups of humans adapt to high-meat, high-fat, hunter-gatherer diets from large land and marine mammals high in certain types of omega-3 and omega-6 fatty acids, says Matteo Fumagalli, a researcher at University College -- London, who is joint first author of the study. They may have arisen among the original Siberians, who have lived in the Arctic for more than 20,000 years, and arrived in Greenland when Inuit settled there about 1,000 years ago.
...
The researchers discovered another common mutation in a gene that is involved in the differentiation of brown, subcutaneous fat cells and brite fat cells, the latter of which generate heat. This may also have helped the Inuit adapt to a cold environment.
So your adapted humans would probably go the way of the Inuit - shorter, better fat distribution, and a metabolism suited to process fatty acids better than the rest of us.
Edit with additional sources:
From the Encyclopedia Britannica
Cold adaptation is of three types: adaptation to extreme cold, moderate cold, and night cold. Extreme cold favours short, round persons with short arms and legs, flat faces with fat pads over the sinuses, narrow noses, and a heavier-than-average layer of body fat. These adaptations provide minimum surface area in relation to body mass for minimum heat loss, minimum heat loss in the extremities (which allows manual dexterity during exposure to cold and guards against frostbite), and protection of the lungs and base of the brain against cold air in the nasal passages. Moderate cold favours the tall, stockily built individual with moderate body fat and a narrow nose, for similar reasons. Night cold—often part of a desert environment, where inhabitants must be able to withstand hot, dry daytime conditions as well as cold at night—favours increased metabolic activity to warm the body during sleep.
Finland is actually relatively temperate - average first snowfall is November in the southern, heavily-populated latitudes. Compare that to Iqualuit, with an average high in July of 12 degrees. So your adapted humans are going to trend stocky and padded.
As for comments w/r to sports promoting growth - there is no correlation between sport and height. Nutrition plays a part, and certainly you'd see muscular growth, but height is dictated by nutrition and genetics.
The important detail, of course, is how long your humans have to adapt; in a space of a century or two, they're not going to look significantly different from their progenitors. But they're going to trend shorter and stockier as each generation passes.
